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Documentation

Image Acquisition interface for GStreamer 1.0

Interface: GStreamer
Revision: 18.11.4
Date: 2021-02-15

General

This page provides the documentation of the HALCON GStreamer image acquisition interface, which is based on GenICam GenTL and GStreamer multimedia library to acquire images from live sources. Registered customers can download the latest revision of this interface from the MVTec WWW server.

System Requirements

  • Linux with kernel 2.6 (or higher).
  • A working installation of GStreamer 1.0 multimedia library with all required kernel modules for the acquisition hardware to be used and at least the base plugins from GStreamer.
  • In some cases, the user running HALCON will need to be in the video group in order to be able to access some devices (e.g. V4L2 devices).
  • HALCON image acquisition interface hAcqGStreamer.so or hAcqGStreamerxl.so, respectively. If you have properly installed the interface, the shared objects should reside in lib\$HALCONARCH within the HALCON base directory $HALCONROOT you have chosen during the installation of HALCON.
  • GenICam version 3.0.2 . The corresponding files are part of the HALCON runtime installation and are located in the directory genicam within the HALCON base directory %HALCONROOT%.

Interface Versioning

MVTec interfaces for digital I/O and image acquisition are always compatible to a range of HALCON versions. Therefore, the versioning scheme both describes the compatibility of the interface and also the revision of the interface itself. An interface version always consists of three numbers, separated by dots, i.e. 18.11.5. The first two numbers describe the minimum HALCON version the interface is compatible with. For the example version 18.11.5 this means that the interface is compatible with all HALCON versions since HALCON 18.11. The last number describes the revision of the interface, in this example this is revision 5.

Installation

Only when installing or updating the interface manually follow these steps:
  • Linux: Extract the archive containing the interface files to the HALCON base directory $HALCONROOT.

Features

  • Support of building and running a GStreamer pipeline using launcher syntax.
  • Grabbing from multiple pipelines.
  • Flexible device lookup and connection options.
  • Synchronous and asynchronous grabbing.
  • Support of callbacks for feature change notifications.
  • Software control of appsink plugin parameters using GenApi.
  • Support for the following GStreamer pixel formats: GRAY8, GRAY16_LE, BGR, RGB, BGRA, RGBA, YUY2, bggr, grbg, rggb, gbrg, UYVY and IYU1.

Limitations

  • No external triggering.

Pipeline Creation and Usage

This interface uses the same pipeline syntax as the tool gst-launch-1.0 that is part of a GStreamer installation. For the interface, there are two ways of creating a pipeline:
  • Call info_framegrabber with 'info_boards' or 'device' parameter to discover the available devices and use the obtained string in open_framegrabber. In this case, the interface will try to generate a compatible pipeline with the available information. However, this does not always work as expected and the initialization may fail due to incompatibilities between plugins in the suggested pipeline.
  • Directly specify the pipeline on open_framegrabber. This is the recommended way for most use cases. When using it, immediate feedback is provided in case of failure. The way to provide the string in open_framegrabber is to prepend the pipeline with #PIPE#, as it can be seen in the following small example:
     
    #PIPE# videotestsrc ! video/x-raw,format=RGB ! appsink 
    
    All pipeline strings given to the interface must use the appsink plugin at the end of the pipeline. The interface will try to find this element in the pipeline and use it to get the frames from the stream. If the appsink plugin is not found, an error will be raised. If needed, use a color conversion plugin or specify the format for the PAD to use one of the pixel formats supported by the interface.
    All the configuration of the acquisition must be provided using the pipeline string. The GStreamer interface does not allow to reconfigure individual elements of the pipeline. If you need to modify a property of the pipeline, you will have to specify the pipeline again and create it anew. For this reason, features such as Width, Height and PixelFormat are marked as read only. Notable exceptions to this are the MaxBuffers and DropBuffers features, that are properties of the appsink plugin and that can be changed at runtime.

On initialization, the GStreamer interface will create the pipeline and momentarily set it to PLAYING in order to query and calculate properties of the images such as Width, Height, PixelFormat and PayloadSize. After this information is successfully queried, the pipeline will be returned to the READY state until the user initializes the acquisition.

GenICam GenApi

  • This interface uses GenApi version version.genapi, for more details refer to the GenICam homepage. The corresponding files are part of the HALCON runtime installation and are located in the directory genicam within the HALCON base directory %HALCONROOT% or $HALCONROOT, respectively. This version is the same as the officially released version at the time of writing.
  • The HALCON GStreamer interface sets all necessary environment variables on its own and ignores other installed GenICam packages by default.
    If you want to use another GenICam package, you need to set the environment variable HALCON_USE_EXTERNAL_GENAPI. This skips the step of setting all necessary variables and paths internally, so you have to make sure they are set correctly. Please note that it might not be possible to use different GenApi versions with different interfaces at the same time and that you must use the required GenApi version for this interface.
  • The caching of device XML files is activated to speed up processing, writing to a temporary directory subject to availability of %TEMP%, %TMP%, $TMPDIR, /tmp or %HALCONROOT%.
  • The remote device control features as well as the GHACHI Producer control features of this interface are controlled via GenApi.

Selection of GenICam Feature Description File(s)

The features of a device or GHACHI Producer are described by GenICam feature description files (XML files) that are automatically parsed and offered to the user. The HALCON GStreamer image acquisition interface provides access to the features exposed through the following GenICam feature description files:
  • Features of the connected device ("remote device"), typically a camera, are usually loaded directly from the connected device.
  • Features of the GHACHI Producer are exposed through a set of GenICam description files, one for each internal entity to control the device tree:
    • The "system" – representing the overall behavior of the acquisition interface
    • The interface used to connect the device to the system.
    • A proxy (called "local device") to the device, controlling the GHACHI Producer view of the device.
    • The data stream used for the acquisition (if the device provides any data streams).
In most cases the GenICam description files are provided by the device and the GHACHI Producer. It is possible to store a copy of these files corresponding to an open connection by using the parameter 'do_write_configuration' (see set_framegrabber_param). The command will write all the GenICam description files and an "ini" file (details in set_framegrabber_param) with various information, including the location of the written GenICam description files, in the following format:
 
RemoteFile=%PATH_TO_GENICAM_FILE_OF_THE_DEVICE% 
SystemFile=%PATH_TO_GENICAM_FILE_OF_THE_SYSTEM_MODULE% 
InterfaceFile=%PATH_TO_GENICAM_FILE_OF_THE_INTERFACE_MODULE% 
DeviceFile=%PATH_TO_GENICAM_FILE_OF_THE_LOCAL_DEVICE_MODULE% 
StreamFile=%PATH_TO_GENICAM_FILE_OF_THE_STREAM_MODULE% 
The same ini-file format can be reused to force the HALCON acquisition interface to load an alternative XML file for one or more of these entities. This can be useful, e.g., for updates or troubleshooting. The files listed in the ini file will be used for the given entity instead of the original ones. For the entities excluded from the ini file, the GenICam description file will be searched and loaded the usual way. To apply the ini file, pass its full path to open_framegrabber in the 'CameraType' parameter.

Note that the ini-file can be reused also for other purposes such as storing/restoring configuration as described in Parameters – Persisting Device Status. Be aware that when persistence files are specified, they have priority over other explicit settings passed to open_framegrabber.

Parameters – Naming Conventions

The following groups of parameters exist:
  • Internal parameters of the HALCON GStreamer image acquisition interface itself. These are named following the "underscore" naming style, e.g., color_space, and are all lowercase.
  • GenICam-based parameters of the device, usually a camera, use by convention the "CamelCase" style, e.g., ExposureTime.
  • GenICam-based parameters of the individual GHACHI Producer modules (system, interface, device and data stream) use by convention the same style but are prefixed with the module name in square brackets. Beware that the system and interface modules might potentially be shared by multiple opened devices, so changing their configuration might have side effects on other connections as well. The following prefixes are used:
    • "[System]", e.g., [System]TLVendorName.
    • "[Interface]", e.g., [Interface]InterfaceType.
    • "[Device]", e.g., [Device]DeviceID.
    • "[Stream]", e.g., [Stream]StreamBufferHandlingMode.

Parameters – Sharing Among Devices

The parameters belonging to the system and interface modules of the GHACHI Producer (i.e. those with "[System]" and "[Interface]" prefix see Parameters – Naming Conventions ) must be treated in a special way.
To grasp their behavior, it is important to understand that they do not describe or configure the device itself and do not thus fully belong to the opened instance of the device.
The interface module parameters belong to the interface on which given device was discovered and is shared among all devices open under this interface (see also ). The system module parameters belong to the entire GHACHI Producer and are shared among all devices open within this GHACHI Producer.
This has several implications. In particular, when accessing the system or interface module parameters through multiple device instances, those parameters must be treated as shared resources. Modifying those parameters through one device instance affects their values (and possibly values of other features depending on them) as seen through other device instances. Initial values of those parameters after opening a device instance might depend on the interactions with these features from previously opened device instances.

Parameters – GenICam Data Types

HALCON native parameter types are
  • integer – signed integer, 64-bit on 64-bit platforms, 32-bit on 32-bit ones
  • real – floating point type
  • string – classical string
When accessing GenICam-based features, the GenICam data types must be mapped to the parameter types recognized by HALCON. GenICam offers the following types:

Parameters – Persisting Device Status

The current status of the acquisition device settings (values of all the parameters defining its working state) might be persisted while no acquisition is active, i.e. before grab_image_start or grab_image_async or after set_framegrabber_param(..., 'do_abort_grab', 1). This applies not only to actual device parameters, but also to parameters configuring the GHACHI Producer and internal parameters of the GStreamer image acquisition interface. Device parameters are usually kept until the device is powered down. The GHACHI Producer modules and the Consumer parameters are kept until close_framegrabber is called. To indicate which parameters to persist, use the parameter 'settings_selector'. The persistence functionality consists of two steps, storing the current configuration to a file and later re-loading it back to the device. The selected module settings, indicated by 'settings_selector', can be stored using the 'do_write_settings' parameter and re-loaded later using the 'do_load_settings' parameter, specifying the desired persistence file path in both cases. To query if a feature can be persisted use the postfix '_streamable'.

Note that while the format of the files is intentionally human readable and the files can be hand-modified if desired, such modifications should be done with care by someone familiar with the GenICam persistence functionality internals and given device. Improper modifications of the files can lead to errors when using it.

It is important to know that while performed by the software, persistence of the device-related features is actually a device-side function. If the persistence support is implemented incorrectly or incompletely by the device, it will not work as expected – in such a case the manufacturer could provide additional information or help.

The same persistence files can be applied to the entire set of devices of the same type and firmware version. Applying the persistence files to a device of another type or using even different firmware version will probably lead to inconsistencies or will even fail completely – the corresponding device manufacturer should provide guidelines for such use cases.

Apart from the 'do_write_settings', the feature persistence file will also be written together with the ini file documented in the section Selection of GenICam Feature Description File(s) - using parameter 'do_write_configuration'. This command will generate extended version of the persistence file, storing not only the current device configuration, but also contents of its user sets and sequencer sets (if the device supports them). Additionally, it will also generate persistence files for all the GHACHI Producer modules (system, interface, device and data stream). The persistence file entries in the ini file will have the format
 
RemotePersistence=%PATH_TO_PERSISTENCE_FILE_OF_THE_DEVICE% 
SystemPersistence=%PATH_TO_PERSISTENCE_FILE_OF_THE_SYSTEM_MODULE% 
InterfacePersistence=%PATH_TO_PERSISTENCE_FILE_OF_THE_INTERFACE_MODULE% 
DevicePersistence=%PATH_TO_PERSISTENCE_FILE_OF_THE_LOCAL_DEVICE_MODULE% 
StreamPersistence=%PATH_TO_PERSISTENCE_FILE_OF_THE_STREAM_MODULE% 
If the persistence functionality is not supported properly (or at all) by a given device, use the GenICam features UserSetSave/UserSetLoad, if supported by the device. These features will allow to store/load the device settings in the device's non-volatile memory.

Acquisition – Overview, Device Control

The image acquisition can be either synchronous (grab_image/grab_data) or asynchronous (grab_image_start/grab_image_async/grab_data_async), see the reference documentation of the operators.
The interface fully configures and controls the acquisition process on the camera. GStreamer pipeline. Note that some of the camera features might be locked by GenICam when an acquisition is active.
With synchronous grab (grab_image/grab_data), a new acquisition is started internally for each image, so that the application always gets a new image. Before delivering the image, the acquisition is stopped again, so between individual grab_image/grab_data calls, all acquisition related features remain unlocked.
With asynchronous grabbing, started explicitly by grab_image_start or implicitly by grab_image_async/grab_data_async, the interface keeps the acquisition running internally, collecting further images to be delivered through future grab_image_async/grab_data_async calls. The acquisition related features are locked, until the acquisition is stopped using set_framegrabber_param(..., 'do_abort_grab', ...).
Note that the interface properly recognizes the 'Continuous', 'SingleFrame' and 'MultiFrame' acquisition modes configured on the device and adjusts the acquisition control logic accordingly.
Note that the HALCON acquisition interface itself takes over exclusive access to several remote device features essential for the acquisition control (AcquisitionStart, AcquisitionStop, AcquisitionAbort, TLParamsLocked). The user application has no direct way to control these features.
The differences between the "image" and "data" version of the grab operators is documented in Acquisition – Grab Operators.

Acquisition – Buffer Handling

The interface allocates 4 buffers for the acquisition engine by default (the number of buffers can be changed through the 'Generic' parameter of open_framegrabber).
Whenever a new image is acquired successfully and passed to the application as a HALCON image, the interface keeps the buffer locked (not returning it to the acquisition engine) until a new grab-related operator is called by the application or the acquisition is aborted using set_framegrabber_param(..., 'do_abort_grab', ...). During this period, it is fully safe to query information about this "last acquired" buffer – for example query buffer properties through get_framegrabber_param parameters such as 'buffer_timestamp', 'buffer_is_incomplete', 'image_width' and 'image_height'. This applies also to eventually present in the buffer and is also usable in volatile mode.
When a new grab-related operator is called by the application, the interface returns the buffer to the acquisition engine and buffer-related queries are not valid anymore.

It can happen, that the camera is temporarily or constantly acquiring data in higher speed than the application is processing them. In such case the streaming engine of the GHACHI Producer decides how to treat the acquired buffers based on the '[Stream]StreamBufferHandlingMode' parameter.

Note that the streaming engine behavior can be further controlled through additional parameters described in
.

Acquisition – Image Format Handling

With modern, generic image acquisition interfaces an application cannot make valid assumptions about the image format coming from the device based on the current settings. Some devices for example allow changing the image format properties while the acquisition is active.
The HALCON GStreamer image acquisition interface fully supports these use cases. It checks the image format and other important properties of every single buffer and generates HALCON images corresponding to both the acquired image format and eventual user configured output format parameters such as 'color_space' and 'bits_per_channel'. Only if the necessary information about the buffer are missing , the current settings are used as a fallback.

Acquisition – Grab Operators

The acquisition interface provides two mechanisms for acquisition of the image (or other) data from the device, grab_image/grab_image_async and grab_data/grab_data_async. Each of them might be more suitable for different use cases. Internally, both mechanisms work exactly the same (in particular how they acquire and process the data from the device), they differ in the way how the outputs are provided to the application.
The "traditional" grab_image/grab_image_async operators are still well suitable in simple use cases when just a single 2D image is acquired from the device. It is also currently used e.g. by the HDevelop's Image Acquisition Assistant. However, in case when the device is streaming more complex data structures, such as 3D data, multi-AOI or similar data, grab_image/grab_image_async is not able to provide all the outputs. In all these cases it will simply provide the first image found in the acquired data.
The "extended" grab_data/grab_data_async operators allow to output arbitrary number of HALCON images and also arbitrary number of control data. It is therefore suitable for use in advanced use cases when more than just a single HALCON image should be output. An important use case is acquisition from 3D devices () when the operators can build and output the 3D object model through the control data output. It can be also used in other (possibly even device-specific) situations when the device outputs multiple images for a single acquisition.
The structure of the provided outputs can be queried with help of the 'image_contents', 'data_contents' and related parameters.
The
grab_data/grab_data_async can also be used in the simple single-image use cases - in that case they will simply provide a single HALCON image and zero control data outputs. They can thus be used as full replacement of the traditional grab_image/grab_image_async operators.

Feature Change Notifications

It is possible to receive notifications about changes of any features exposed through the GenICam interface by the camera and GHACHI Producer.
Note that the notifications might be raised in various circumstances, including:
  • The application (you) explicitly changed that feature.
  • Another feature has changed and the notified feature "depends" on the changed feature (the dependencies are defined in the GenICam description file).
  • Access mode or current range for the feature has changed.
  • As a result of regular "polling" in case of uncached features.
  • As a result of device event delivery if the feature is connected to that event.
  • As a result of new buffer delivery for features corresponding to chunk data.
Note that the notifications are raised whenever the feature is "marked dirty" (its cache invalidated) by one of the actions described above. It does not necessarily mean that its value has really changed, it is up to the application to check this.
Notification callbacks can be registered for individual features using set_framegrabber_callback - see corresponding operator documentation. Additionally, it is possible to use message queues to receive the event notification. In those cases it is necessary to create a message queue and then register the individual feature - see event message queues.

Event Data

GenICam compatible devices can deliver asynchronous events which optionally carry additional data. It is usually necessary to enable delivery of individual event types using the features 'EventSelector'/'EventNotification' first. For SFNC-compliant events, this is done automatically if the parameter 'event_notification_helper' is enabled.
The decoding of the event data and matching them to the corresponding features, including potential notifications, is performed transparently by the interface.
The actual values might be read through the regular parameter reading mechanism like get_framegrabber_param or by get_message_tuple if you are using message queues to receive events. The choice of the event types to be generated is device-specific. The names of the event related features usually start by convention with a prefix 'Event' (examples might be 'EventFrameTrigger' and 'EventFrameTriggerTimestamp'), however, the device documentation should contain all the information about supported events and their corresponding feature names.
Although the data corresponding to the last delivered event can be in general read at any time, when using callback to receive events it is highly recommended that reading the event data is synchronized to notifications for corresponding event feature(s). Only in such a case it is guaranteed that the read data correspond exactly to the very event instance being notified – and that the feature values are not just being modified through a new instance of the same event. Note that the notifications are raised from context of the event handling/dispatching thread, so when processing the user callback, the event handling mechanism is paused. If multiple data items are associated with the same event, it is enough to register notification just for the actual event feature and read all the data during the callback.
If using message queues to receive events, you can decide to add additional data to be delivered with the corresponding event feature(s), see Event Message Queues. For this case the interface will read all the specified event features as soon as the event is generated and add it to the corresponding message. This guarantees that the delivered information corresponds with the actual value at the time the event was generated.
Besides the asynchronous events generated by the actual device, asynchronous events (optionally including additional data) can be generated by any module of the GHACHI Producer (system, interface, device and data stream). The information provided above about handling of the device events applies similarly also to the GHACHI Producer events, including enabling/disabling them (typically using 'EventSelector'/'EventNotification' features provided by given module, i.e. with corresponding module prefix in the feature name). For SFNC-compliant events, this is done automatically if the parameter 'event_notification_helper' is enabled.
The interface will automatically capture and decode the events and match them to the corresponding GHACHI Producer features. It is only important to understand that because the system and interface modules are potentially shared among multiple opened devices (see Parameters – Sharing Among Devices) and so, the same applies for asynchronous events generated by these shared modules.

Event Message Queues

This interface supports feature change notifications via message queues. Select the desired target feature with set_framegrabber_param(..., 'event_selector', ...). It is the same plain feature name as used with set_framegrabber_param, including a possible prefix, such as '[Device]' (refer to the Parameters – Naming Conventions).
Create a message queue at which you want to receive the notifications with create_message_queue and assign it to the selected feature with set_framegrabber_param(..., 'event_message_queue', QueueHandle).
The message queue can be registered for any GenICam based features, i.e., features published by the device and GHACHI Producer through the GenICam description files. The list of supported targets can be queried by calling get_framegrabber_param(..., 'available_event_names', ...).
One of the important use cases for feature change callbacks is the device event delivery mechanism, see details in Event Data and Feature Change Notifications sections.
A new message would be added to the specified queue whenever a given feature is potentially changed (including its other properties such as range or access mode). Note that it does not necessarily always mean that the feature actually has a new value. set_framegrabber_param(..., 'event_message_queue', 0) unregisters the previously registered message queue from the specified event. Note that the interface keeps just a single registration for every feature, if you attempt to register a new message queue for a feature that already had a message queue registered, the previous registration will be replaced with the new one.
The messages incoming on an event can be retrieved with dequeue_message and will contain at least three tuples. The first tuple (key 'id') is a unique identifier of the acquisition instance the event is coming from. It is a string composed as '<interface>:<device>'. The second tuple (key 'event_name') is the name of the corresponding feature previously specified by 'event_selector'. The third tuple (key 'event_value') contains the value if the corresponding feature if available. If you decide to add additional data to be delivered with the corresponding event feature(s), add the features of interest with set_framegrabber_param(..., 'event_data', ...). Each event data feature will be appended to the event message with the key being its name and the tuple its value if available.

Using HDevelop Image Acquisition Assistant

In case of using the HDevelop Image Acquisition Assistant the following hints will help to avoid problems:
  • Some parameters depend on special conditions, e.g., a valid buffer or another parameter activated. After opening the camera these conditions may not yet be fulfilled, so the depending parameters are not shown. By using the 'Refresh' button, all parameters are read again and the depending parameters should appear if the conditions are fulfilled then.
  • There are also some parameters regarding the image size and the payload size, which can only be changed if no acquisition takes place. The safest way to ensure this is to apply the action parameter 'do_abort_grab'. Please note that 'Update Image' has to be disabled first.
  • The behavior of allowing changes to parameters while streaming is active depends on the capabilities of the device. It is possible that some cameras give you control over, e.g., the exposure time, while streaming and others do not.

Using Internal Color Conversion

The HALCON GStreamer interface supports an internal color conversion performed in software. The conversion is automatically applied for PFNC (Pixel Format Naming Convention) compatible cameras, when the color format delivered by the camera differs from the user defined format if set via the parameter 'color_space'. The used transformation algorithms are basic and optimized for speed.

Following transformations from the camera color space (see also PFNC) to the interface color space (see also 'color_space' parameter in this document) are supported:

  • Bayer pattern to 'rgb':

    Bayer_LMMN
    R G1
    G2 B
    [R,G,B] [R,G,B]
    [R,G,B] [R,G,B]
    Bayer_NMML
    B G1
    G2 R
    [R,G,B] [R,G,B]
    [R,G,B] [R,G,B]
    with G = (G1 + G2) / 2.

  • Y'CbCr to 'rgb' (Note: gamma correction is not considered):

    R = Y' + 1.4020 * (Cr- M)
    G = Y' - 0.34414 * (Cb- M) -0.71414 * (Cr- M)
    B = Y' + 1.7720 * (Cb - M)

  • RGB to 'yuv' ('yuv' corresponds to Y'CbCr of PFNC, Note: gamma correction is not considered):

    Y' = 0.299 * R + 0.587 * G + 0.114 * B
    Cb = -0.16874 * R - 0.33126 * G + 0.5 * B + M
    Cr = 0.5 * R - 0.41869 * G - 0.08131 * B + M

  • RGB to 'gray':

    Y' = 0.299 * R + 0.587 * G + 0.114 * B

with M = 128 for 8 bit raw data, and M = 32768 for 16 bit raw data.
The accuracy of the results is limited due to internal 16.16 fix-point arithmetic for 8 bit ( 0...255), and 24.8 fix-point arithmetic for 16 bit raw data.

Parameters for info_framegrabber

Parameter Value List Type Kind Description
'bits_per_channel' [-1, 8, 10, 12, 14, 16] integer pre-defined Values for bits per channel.
'camera_type' ['CAMFILE:', 'ini;xml', '<path>', 'default'] string pre-defined Syntax for connection configuration file and default value.
'color_space' ['default', 'gray', 'raw', 'rgb', 'yuv'] string pre-defined Values for color space.
'defaults' [0, 0, 0, 0, 0, 0, 'progressive', -1, 'default', -1.0, 'false', 'default', '0', 0, 0] mixed pre-defined Default values for open_framegrabber.
'device' [' | device:<device id> | unique_name:<unique name> | user_name:<user-defined name> | interface:<interface id> | producer:Ghachi'] string dynamic List of GStreamer devices discovered in the system with information about their device ID, unique name, user-defined name and interface ID. See the full description in section about device opening. This call will always return at least one virtual device that uses default pipeline with videotestsrc.
'external_trigger' ['false', 'true'] string pre-defined Values for the external trigger.
'field' [] Unused.
'general' [] string pre-defined Information about the HALCON GStreamer interface.
'generic' ['', 'num_buffers=<num>', 'workarounds=<list>'] string pre-defined Value list for the Generic parameter.
'horizontal_resolution' [0, 1] integer pre-defined Value list for horizontal resolution.
'image_height' [] Unsupported query.
'image_width' [] Unsupported query.
'info_boards' [' | device:<device_id> | unique_name:<unique_name> | user_name:<user_defined_name> | interface:<interface_id> | producer:Ghachi | vendor:<device_vendor> | model:<device_model> | tl_type:<tl_type> | status:<device_status> | suggestion:<generic_param>']status:<device_status> | suggestion:<generic_param>'] List of GStreamer video devices discovered by gst-device-monitor-1.0. This call will always return at least one virtual device that uses default pipeline with videotestsrc.
  • <b>device_id</b> is the name of the device, which will be shown by info_framegrabber<tt>(...,'device',...)</tt>. If a user_name (or 'DeviceUserID') is set, then this will be shown. Otherwise the unique_name is used.
  • <b>unique_name</b> is a unique identifier for the device. The format of the string depends on the type of transport layer.
  • <b>user_name</b> represents the value of the feature 'DeviceUserID', which is a user-defined name for the device.
  • <b>interface</b> shows the hardware interface by which the device is connected to the PC. For transport layer type 'GEV' for example, this is the MAC address of the network card.
  • <b>producer</b> shows the name of the underlying GenICamTL producer.
  • <b>vendor</b> represents the value of the feature 'DeviceVendorName'.
  • <b>model</b> represents the value of the feature 'DeviceModelName'.
  • <b>tl_type</b> shows the type of the underlying transport layer. In this interface the value will always be 'Custom'.
  • <b>status</b> shows, if the device is correctly configured or not. The possible values are 'available', 'read-only', 'busy', and 'unknown'. Even devices that are currently not available for opening are listed.
string dynamic A list of the available devices.
'parameters' ['<parameters>'] string pre-defined Pre-defined parameters of the HALCON interface.
'parameters_readonly' ['<parameters>'] string pre-defined Pre-defined read-only parameters of the HALCON interface.
'parameters_writeonly' ['<parameters>'] string pre-defined Pre-defined write-only parameters of the HALCON interface.
'port' [] Unused.
'revision' '<revision>' string pre-defined Revision number of the GStreamer interface.
'start_column' [] Unsupported query.
'start_row' [] Unsupported query.
'vertical_resolution' [0, 1] integer pre-defined Value list for vertical resolution.

Parameters for open_framegrabber

Parameter Values Default Type Description
Name 'GStreamer' string Name of the HALCON interface.
HorizontalResolution 0, 1, resolution 1 integer Set the desired horizontal resolution of the camera image:
  • 0: Keep the current Width settings of the camera.
  • 1: If vertical_resolution is also set to 1, configure full resolution of the camera using GenICam SFNC features (resetting binning/decimation features and setting the image size to maximum).
  • resolution: Use the value directly as image Width.
VerticalResolution 0, 1, resolution 1 integer Set the desired vertical resolution of the camera image:
  • 0: Keep the current Height settings of the camera.
  • 1: If horizontal_resolution is also set to 1, configure full resolution of the camera using GenICam SFNC features (resetting binning/decimation features and setting the image size to maximum).
  • resolution: Use the value directly as image Height.
ImageWidth --- 0 Ignored.
ImageHeight --- 0 Ignored.
StartRow --- 0 Ignored. Configure the image size through device parameters.
StartColumn --- 0 Ignored. Configure the image size through device parameters.
Field --- Ignored.
BitsPerChannel -1, 8, 10, 12, 14, 16 -1 integer Number of bits per channel of the resulting HALCON image. In case of -1 the bit depth of each respective acquired buffer is used. By specifying a value greater than 8 the grabbed images are delivered as uint2 images.
ColorSpace 'default', 'gray', 'raw', 'rgb', 'yuv' 'default' string Specify the desired color space and thus the number of image channels of the resulting HALCON image. In case of 'default' for Mono pixel formats, ColorSpace is set to 'gray', otherwise to 'rgb' (and for unknown pixel formats to 'raw').
Generic '', ['num_buffers=<num>', 'workarounds=<list>'], -1 -1 mixed With the Generic parameter some important values can be set before the camera is initialized. Note that the parameter names including the values must be strings, e.g., 'num_buffers=5' sets the number of buffers to 5.
The following parameters are available:
  • num_buffers: To set the maximum number of acquisition buffers used. Note that depending on the image size of the used camera a high number of buffers can exceed the available memory size of your computer. We recommend to use at least 2 buffers. Notice that the interface internally locks 1 buffer (see acquisition buffer handling), therefore if your application requires n buffers, 'num_buffers' must be set to n+1. Default: 4.
  • workarounds: Enables one or more of the workarounds supported by the GStreamer image acquisition interface. The workarounds are options slightly altering the image acquisition interface behavior in order to cope with some common problems of devices and pipelines . The individual workaround names might be listed using any separator, for example a space or comma. Supported workarounds are:
    • enable_range_validation: When this workaround is enabled, an additional check is performed when querying the range of a parameter: check if min
ExternalTrigger 'false', 'true' 'false' string Status of the external trigger.
CameraType 'default', <ini/xml filename> 'default' string Full path to the configuration file with the specification of alternative GenICam description files to be loaded for the device and GHACHI Producer, see detailed description in section about device opening.
Device ' | device:<device id> | unique_name:<unique name> | user_name:<user-defined name> | interface:<interface id> | producer:Ghachi', '<device id>' string To open a camera, the device name as shown in info_framegrabber(...'device'...) or info_framegrabber(...'info_boards'...) can be used. Some of the string entries might be skipped or set as 'default'. To open a specific camera, either device or unique_name has to be set. As a shortcut, only the device ID or user-defined name might be specified or the string 'default' can be used. See full description in section about device opening.
Port --- Unused.
LineIn --- Ignored.

Parameters for set_framegrabber_param

The parameters of the cameras and GHACHI Producer are accessed through GenICam and defined in GenICam description file(s) of the respective camera or GHACHI Producer, so the parameter set is different for every product (although the parameter naming should adhere to SFNC GenICam standard). A call of get_framegrabber_param(..., 'available_param_names', ...) returns a tuple containing all available parameters of the connected camera and GHACHI Producer. See also section about parameter naming convention.
To set e.g. the current gain of the camera AcqHandle refers to (after calling open_framegrabber), the user can call set_framegrabber_param(AcqHandle, 'Gain', 6.0).
Please note that the interface sets the value of a parameter only if the value is valid. Integer and float values not matching the allowed range for given feature are aligned to the closest valid value. Invalid values of other feature types are refused.
Additionally to the GenICam parameters of the camera and of the GHACHI Producer, the following HALCON interface parameters are supported by set_framegrabber_param:
Parameter Values Default Type Description
'[Device]DeviceEventsThreadApplyPriority' --- integer Applies the thread priority and scheduling policy (if applicable on given operating system) configured through the '[Device]DeviceEventsThreadPriority' and '[Device]DeviceEventsThreadSchedulingPolicy' parameters to the event processing thread. If the thread is running, the values are directly applied. If the thread is not running in the moment, the values are stored and will be applied as soon as the thread is started again. It is responsibility of the application to ensure that the calling process has sufficient privileges.
The feature is not available for devices not supporting device events or if the event handling was disabled using the 'device_event_handling=0' generic parameter.
BEWARE: Setting this parameter can lead to an unusable or poorly performing system, use with care.
'[Device]DeviceEventsThreadPriority' <thread_priority> integer OS-specific thread priority value to be used for the internal event processing thread. The actual values are directly the priority identifiers of the operating system, e.g. THREAD_PRIORITY_HIGHEST under Windows or a real-time priority value under Linux.
The actual priority is applied only after executing the '[Device]DeviceEventsThreadApplyPriority' command parameter, possibly together with the '[Device]DeviceEventsThreadSchedulingPolicy' value if applicable on given system.
It is the responsibility of the application to ensure that the calling process has sufficient privileges to apply the priority change and that the value written to the parameter is a valid priority identifier. After applying '[Device]DeviceEventsThreadApplyPriority', the application can read back the priority value to verify if it was properly applied.
Note that when opening the device, the GHACHI Producer attempts itself to elevate the thread priority to a suitable value.
The feature is not available for devices not supporting device events or if the event handling was disabled using the 'device_event_handling=0' generic parameter.
BEWARE: Setting this parameter can lead to an unusable or poorly performing system, use with care.
'[Device]DeviceEventsThreadSchedulingPolicy' <scheduling_policy> integer OS-specific scheduling policy value to be used for the internal event processing thread. The actual values are directly the priority identifiers of the operating system, e.g. SCHED_FIFO under Linux. Note that this feature is not available under Windows.
The actual scheduling policy is applied only after executing the '[Device]DeviceEventsThreadApplyPriority' command parameter, together with the '[Device]DeviceEventsThreadPriority' value.
It is the responsibility of the application to ensure that the calling process has sufficient privileges to apply the scheduling policy and that the value written to the parameter is a valid scheduling policy identifier. After applying '[Device]DeviceEventsThreadApplyPriority', the application can read back the scheduling policy value to verify if it was properly applied.
The feature is not available for devices not supporting device events or if the event handling was disabled using the 'device_event_handling=0' generic parameter.
BEWARE: Setting this parameter can lead to an unusable or poorly performing system, use with care.
'[Stream]StreamBufferHandlingMode' 'OldestFirst', 'OldestFirstOverwrite', 'NewestOnly' 'OldestFirst' string Selects the mode the streaming engine uses to handle newly acquired data, in particular when the camera runs faster than the application processing. The parameter is writeable only if no acquisition is active. Supported values are:
  • 'OldestFirst': The acquired buffers are always delivered in FIFO manner (oldest first). If the acquisition engine receives a new buffer from the camera but has no available free buffer to fill it in, the new data is discarded.
  • 'OldestFirstOverwrite': The acquired buffers are always delivered in FIFO manner (oldest first). If the acquisition engine receives a new buffer from the camera but has no available free buffer to fill it in, it checks, whether there are older buffers waiting for delivery, not yet picked up by the Consumer. If yes, it takes the oldest of them, overwrites it with the new data and appends it to the end of the output queue. If the output queue is empty (no buffer available for overwriting), the new data is discarded. Applicable for socket driver only, undefined behavior with filter driver.
  • 'NewestOnly': The output queue of buffers waiting for delivery never contains more than a single (newest) buffer. If the acquisition engine receives a new buffer and there is already an older buffer waiting for delivery in the output queue, the new buffer is put to the output queue instead and the old one is reused for next acquisition. If there are no available free buffers and the output queue is also empty, new data is discarded.
'[Stream]StreamThreadApplyPriority' --- integer Applies the thread priority and scheduling policy (if applicable on the given operating system) configured through '[Stream]StreamThreadPriority' and '[Stream]StreamThreadSchedulingPolicy' parameters to the stream processing thread. If the thread is running (acquisition started), the values are directly applied. If the thread is not running in the moment, the values are stored and will be applied as soon as the thread is started again. It is the responsibility of the application to ensure that the calling process has sufficient privileges.
BEWARE: Setting this parameter can lead to an unusable or poorly performing system, use with care.
'[Stream]StreamThreadPriority' <thread_priority> integer OS-specific thread priority value to be used for the internal stream processing thread. The actual values are directly the priority identifiers of the operating system, e.g. THREAD_PRIORITY_HIGHEST under Windows or a real-time priority value under Linux.
The actual priority is applied only after executing the '[Stream]StreamThreadApplyPriority' command parameter, possibly together with the '[Stream]StreamThreadSchedulingPolicy' value if applicable on given system.
It is the responsibility of the application to ensure that the calling process has sufficient privileges to apply the priority change and that the value written to the parameter is a valid priority identifier. After applying '[Stream]StreamThreadApplyPriority', the application can read back the priority value to verify if it was properly applied.
Note that when opening the device, the GHACHI Producer attempts itself to elevate the thread priority to a suitable value.
BEWARE: Setting this parameter can lead to an unusable or poorly performing system, use with care.
'[Stream]StreamThreadSchedulingPolicy' <scheduling_policy> integer OS-specific scheduling policy value to be used for the internal stream processing thread. The actual values are directly the priority identifiers of the operating system, e.g. SCHED_FIFO under Linux. Note that this feature is not available under Windows.
The actual scheduling policy is applied only after executing the '[Stream]StreamThreadApplyPriority' command parameter, together with the '[Stream]StreamThreadPriority' value.
It is the responsibility of the application to ensure that the calling process has sufficient privileges to apply the scheduling policy and that the value written to the parameter is a valid scheduling policy identifier. After applying '[Stream]StreamThreadApplyPriority', the application can read back the scheduling policy value to verify if it was properly applied.
BEWARE: Setting this parameter can lead to an unusable or poorly performing system, use with care.
'add_objectmodel3d_overlay_attrib' 'disable', 'enable' 'disable' string Controls if the acquisition interface should attempt to append the intensity/color overlay to the generated 3D object models. Applicable only if a 3D object model is being output from given grab operator. When switched on, the acquisition interface will try to find suitable information within the acquired data (if it is provided by the device). If so, it appends the overlay information for each point in the output model in form of an extended attribute. Note that in some advanced use cases there might be multiple potential overlay images output by the device, the acquisition interface therefore attempts to find the most suitable one.
First, it tries to identify data marked as "intensity" image in the acquired data. If found and provided as monochrome 2D image, it is appended as '&intensity_gray' extended attribute. If found and provided as RGB image, it is appended as three extended attributes, '&intensity_red', '&intensity_green' and '&intensity_blue'.
If "intensity" data cannot be identified, it tries to find data marked as "reflectance". If found and provided as monochrome 2D image, it is appended as '&reflectance_gray' extended attribute. If found and provided as RGB image, it is appended as three extended attributes, '&reflectance_red', '&reflectance_green' and '&reflectance_blue'.
Finally, if neither "intensity" nor "reflectance" data can be identified (either not present or not correctly marked by the device, it picks the first 2D image within the acquired data than can be mapped to the 3D coordinates. If found and provided as monochrome 2D image, it is appended as '&overlay_gray' extended attribute. If found and provided as RGB image, it is appended as three extended attributes, '&overlay_red', '&overlay_green' and '&overlay_blue'.
If no suitable 2D image is found, no overlay is appended. The actually appended extended attributes can be queried for example using the get_object_model_3d_params operator with the 'extended_attribute_names' parameter. The overlay can be also used for visualization purposes.
'bits_per_channel' -1, 8, 10, 12, 14, 16 integer Number of bits per channel of the resulting HALCON image. In case of -1 the bit depth of each respective acquired buffer is used. By specifying a value greater than 8 the grabbed images are delivered as uint2 images.
'buffer_reallocation_mode' 'only_increase_size', 'follow_payloadsize' 'only_increase_size' string Defines the strategy to follow when reallocating the buffers for a new acquisition. In case of 'only_increase_size', the buffers will be only reallocated when the payload size increases. In case of 'follow_payloadsize', the buffers will be reallocated every time the payload size changes.
'clear_buffer' 'disable', 'enable' 'disable' string If enabled, each buffer content is cleared before re-queueing (all bytes set to 0xF0 regardless the expected pixel format), so you can see which parts of an image are missing, in case e.g. the transfer of some image packets failed. This parameter adds of course a runtime overhead to write the 0xF0 data every time a buffer is queued. It is mainly useful for debugging in combination with transport layers which do not guarantee the transfer of complete images. Please note, that this parameter does not modify the buffer queue, only the content of a buffer will be set to a defined state.
'color_space' 'default', 'gray', 'raw', 'rgb', 'yuv' string Specify the desired color space and thus the number of image channels of the resulting HALCON image. In case of 'default' for Mono pixel formats, ColorSpace is set to 'gray', otherwise to 'rgb' (and for unknown pixel formats to 'raw').
'confidence_mode' 'off', 'object_model_3d' 'off' string Controls if (and how) the information about pixel confidence level is used by the acquisition interface. Applicable only for devices and use cases where the confidence information is delivered (per-pixel) together with the actual pixel data.
The threshold to distinguish between valid and invalid pixels is controlled using the 'confidence_threshold' parameter.
Note that in some use cases there might be other criteria how to mark given pixel invalid, for example if the device uses "invalid pixel value" for a 3D coordinate. These cases are not covered by the 'confidence_mode' parameter and such invalid pixels are always rejected from the 3D object model. Possible values are:
  • off: Default value. The pixel confidence information is not applied to any of the grab operator outputs, even if supplied by the device.
  • object_model_3d: If the pixel confidence level information is available, it is applied to the eventually generated 3D object models (but not to any other outputs, in particular not to the image outputs). This means that pixels ("points") with confidence lower than the configured threshold are not included in the generated 3D object model.
'confidence_threshold' [0.0, 1.0] 0.5 float Threshold separating between valid and invalid pixels. Applicable only for devices and use cases where the confidence information is delivered (per-pixel) together with the actual pixel data. The decision how (to which outputs) the confidence threshold is applied is controlled using the 'confidence_mode' parameter.
The threshold is interpreted as a (float) ratio between 0.0 and 1.0. The acquisition interface will remap this ratio to the actual confidence range provided by the device and use it to decide which pixels are valid and which not. Pixels with confidence lower than the specified threshold are considered invalid.
'coordinate_transform_mode' 'none', 'cartesian', 'reference' 'reference' string Controls which coordinate transformation operations should the acquisition interface attempt to perform when building the 3D object model from acquired 3D coordinates. Note that the decision which transformation should be performed and which parameters should be used fully depends on the 3D configuration information provided by the device together with the acquired data. If this information is insufficient or coordinates are inaccurate, the result of the transformation(s) might be meaningless or unpredictable. Refer to for more details.
Possible values are:
  • none: The acquisition interface will not perform any coordinate transformation. The 3D object model will contain the "raw" coordinates, possibly only scaled depending on the hints from the device.
  • cartesian: If the coordinate system used by the device is other than Cartesian, the acquisition interface will convert the coordinates to Cartesian system (native for HALCON's 3D object model). It will not attempt to further transform the coordinates from the device's internal ("anchor") coordinate system to the reference system.
  • reference: Default mode. Will transform to Cartesian coordinates if needed and then attempt to transform to the "reference" coordinate system if the device supports it and provides corresponding instructions. The purpose of the reference system is to allow merging and aligning data from multiple devices. The reference system is in contrast with the native ("anchor") coordinate system which is device specific and corresponds to its actual measurement system and actual configuration.
    The position and orientation of the reference system should be indicated by a reference point marker on the device's housing.
    This always directly implies the transformation to Cartesian coordinates because the reference coordinate system is always Cartesian.
'create_objectmodel3d' 'disable', 'enable' 'disable' string Controls whether the acquisition interface should attempt to generate HALCON 3D object model(s) when encountering 3D coordinates within the acquired data.
To obtain a 3D object model, the application has to use the grab_data/grab_data_async operators which can return the handles to the generated models through the control data outputs. The grab_image/grab_image_async operators cannot return the 3D object models.
IMPORTANT: the parameter is disabled by default. When enabling, the application is responsible for releasing the generated object models and associated resources using the clear_object_model_3d operator once it does not need given model(s) any more. It should do so by tracking which of the control data outputs of every single grab_data/grab_data_async calls carry 3D object model handle(s). This can be done using the 'data_contents' parameter.
When generating the 3D object model, the acquisition interface processes the 3D coordinates found in the acquired data and builds the point cloud with help of the information about the actual 3D configuration reported by the device. Refer to for more details.
'delay_after_stop' <milliseconds> 0 integer The time to wait (in milliseconds) between stopping the acquisition on the device (AcquisitionStop command) and GHACHI Producer.
'do_abort_grab' --- Aborts the current image acquisition and unlocks parameters, that might be locked when acquisition is active. See acquisition overview.
'do_load_settings' <input_file> string Restores the previously stored settings of the opened device. The paramter 'settings_selector' specifies if the settings of the actual (remote) device, one of the GHACHI Producer modules or the Consumer parameters (internal parameters of GStreamer image acquisition interface) are to be restored. See detailed description in section Parameters - Persisting Device Status.
'do_write_configuration' <output_file> string Writes a configuration (ini) file and additionally writes GenICam description files and persistence files with the current configuration of the device into the same directory.
The string parameter must be the filename (including full path) of the target ini file. The path must exist prior to writing. The written ini file contains a list of paths to the written description and persistence files.
GenICam description files are written for the remote device and each GHACHI Producer module associated with currently opened device. Persistence files are written for the remote device and each GHACHI Producer module as well as for the internal parameters of the GStreamer image acquisition interface.
The complete configuration can be loaded using the 'CameraType' parameter of open_framegrabber operator, see detailed description in section about device opening. The persisted values of the internal parameters override the corresponding parameters passed to 'open_framegrabber' (in particular 'BitsPerChannel' and 'ColorSpace').
Instead of specifying the full name of the output ini file, 'default' or an empty string can be used. In this case the files will be written to a temporary directory (subject to availability of %TEMP%, %TMP%, $TMPDIR, /tmp or %HALCONROOT%) and the filename of the configuration file will be halcon_gentl_config.ini. This default option will also apply when using the Image Acquisition Assistant.
See also related sections Selection of GenICam Feature Description File(s) and Parameters – Persisting Device Status.
'do_write_settings' <output_file> string Writes the current settings of the opened device to be able to restore the settings later. The paramter 'settings_selector' specifies if the settings of the actual (remote) device, one of the GHACHI Producer modules or the Consumer parameters (internal parameters of GStreamer image acquisition interface) are to be written. See detailed description in section Parameters - Persisting Device Status.
'DropBuffers' 0, 1 1 integer Controls the behavior when the buffer queue is filled in the appsink element.
'event_data' '<genicam_feature>' string Selects GenICam features to be added to the message queue specified by 'event_message_queue' and 'event_selector'. Features can be added individually or as a tuple. To remove individual features, prepend them with a '~'. To clear all currently added features, call set_framegrabber_param(..., 'event_data', []). Read more about the usage of this mechanism at Event Message Queues.
'event_message_queue' 0, '<queue_handle>' handle Selects a message queue to which the acquisition interface should send Feature Change Notifications. The corresponding GenICam feature needs to be previously specified by 'event_selector'. Read more about the usage of this mechanism at Event Message Queues.
'event_notification_helper' 'disable', 'enable' 'disable' string Controls if the acquisition interface should attempt to automatically (un)set 'EventNotification' during set_framegrabber_callback if the callback is being (un)registered on an SFNC-compliant event. Note that this will only work if the callback is being registered on the actual event feature (e.g. 'EventExposureEnd'), not on one of the event data features (e.g. 'EventExposureEndTimestamp'). For further information on events, see Event Data.
'event_selector' '<genicam_feature>' string Selects a GenICam feature for which the acquisition interface should send Feature Change Notifications. They are sent to the message queue specified by 'event_message_queue'. Read more about the usage of this mechanism at Event Message Queues.
'grab_timeout' <milliseconds> 5000 integer Desired timeout (milliseconds) for aborting a pending grab. If -1 is specified, the timeout is set to INFINITE.
'image_height' --- 0 Unsupported (read-only parameter).
'image_width' --- 0 Unsupported (read-only parameter).
'MaxBuffers' 1 integer The maximum number of buffers (max-buffers) to queue in the appsink element (0 = unlimited).
'PipelineBuild' Builds the pipeline set based on the 'PipelineString' value.
'PipelineString' '<pipeline>' string Pipeline string using the gst-launch-1.0 syntax. The appsink plugin must be set at the end of the pipeline string.
'register_<addr>_<len>' integer Direct register access for reading and writing integers. The value has to be hexadecimal, e.g. 0x0938. Note that only 4 or 8 Byte length values are accepted. Caution: This is a dangerous function intended for debugging and special cases. Usually only features in the XML should be used.
'settings_selector' 'RemoteDevice', 'Stream', 'Device', 'System', 'Interface', 'Consumer' 'RemoteDevice' string Selects for which component (set of parameters) the streamable parameters are persisted into a file or restored from a file when using set_framegrabber_param(..., 'do_write_settings', []) and set_framegrabber_param(..., 'do_load_settings', []). Selects among the actual (remote) device, one of the GHACHI Producer modules or the Consumer parameters (internal parameters of GStreamer image acquisition interface). Read more about the usage of this mechanism at Parameters – Persisting Device Status.
'split_param_values_into_dwords' 'disable', 'enable' 'disable' string Enables a special mode allowing the treatment of integer parameters as tuple of two 32-bit integers. For compatibility with the single-parameter mode, the first tuple element carries always the low 32-bit part of the value, second element carries the high 32-bit part. It is user's responsibility to combine the two parts correctly. This mode is intended especially to help to overcome the problem of 32-bit HALCON featuring only 32-bit integer parameters but having to face up to 64-bit wide GenICam features. In this mode, the get_framegrabber_param returns always a tuple of two integers, set_framegrabber_param accepts both a single parameter or a tuple. Note that this mode affects only integer parameters and only the GenICam based ones, not the internal parameters of HALCON GStreamer image acquisition interface - with few exceptions, the 'buffer_timestamp', 'buffer_timestamp_ns', 'device_timestamp_frequency' and 'buffer_frameid' internal parameters.
'start_async_after_grab_async' 'disable', 'enable' 'enable' string By default a new asynchronous grab command is automatically given to the acquisition device at the end of grab_image_async. If the parameter 'start_async_after_grab_async' is set to 'disable', this new grab command is omitted.
'start_column' --- 0 Unsupported (read-only parameter). Configure the image size through device parameters.
'start_row' --- 0 Unsupported (read-only parameter). Configure the image size through device parameters.
'volatile' 'disable', 'enable' 'disable' string When enabled, switches on the volatile mode in which the image buffers are used directly to create HALCON images. This is the fastest mode avoiding the copy of raw images in memory. However, be aware that older images might be overwritten by the acquisition engine with new data at any time. When changing the device configuration in a way that acquisition buffers must be reallocated, the older HALCON images would even become invalid (pointing to no more existing memory). See also details about acquisition buffer handling.
Please note that the volatile mode can be switched on at any time, regardless of the current configuration. However, at runtime only the acquired images compatible with the volatile mode will be delivered to the application (the others will be discarded). Compatible means in particular that the PixelFormat of the acquired image matches the color_space and bits_per_channel settings configured for HALCON image output format.

Parameters for get_framegrabber_param

There may exist additional read-only parameters with the following postfixes:
  • '_access': These parameters provide the access permissions of the corresponding parameter as a string. Possible values are 'ro' (read-only), 'wo' (write-only), and 'rw' (read/write).
  • '_category': These parameters provide the category of the corresponding parameter as a string.
  • '_description': These parameters provide the tool-tip of the corresponding parameter as a string.
  • '_displayname': These parameters provide the displayname of the corresponding parameter as a string.
  • '_longdescription': These parameters provide the description of the corresponding parameter as a string.
  • '_range': These parameters provide the minimum, maximum, step width, and current values for the corresponding integer or float parameter as a tuple with 4 elements, e.g., get_framegrabber_param(.., 'Shutter_range', ..) will return the output tuple [min, max, step, current].
  • '_type': These parameters provide the type of the corresponding parameter as string.
  • '_values': These parameters provide the valid value list for the corresponding parameter as a tuple, e.g., get_framegrabber_param(.., 'volatile_values', ..) will return the output tuple ['enable', 'disable'].
  • '_visibility': These parameters provide the visibility of the corresponding parameter as a string. Possible values are 'beginner', 'expert', and 'guru'.
  • '_streamable': These parameters provide the persistence of the corresponding parameter as an integer. Possible values are 0 if false or 1 if true.

All these postfixed parameter names are not returned when calling info_framegrabber(.., 'parameters', ..) and are used to enable the easy parameterization via a generic graphical user interface, particularly the HDevelop Image Acquisition Assistant.

Parameter Values Default Type Kind Description
'[Device]DeviceEventsThreadPriority' <thread_priority> integer pre-defined OS-specific thread priority value to be used for the internal event processing thread. The actual values are directly the priority identifiers of the operating system, e.g. THREAD_PRIORITY_HIGHEST under Windows or a real-time priority value under Linux.
The actual priority is applied only after executing the '[Device]DeviceEventsThreadApplyPriority' command parameter, possibly together with the '[Device]DeviceEventsThreadSchedulingPolicy' value if applicable on given system.
It is the responsibility of the application to ensure that the calling process has sufficient privileges to apply the priority change and that the value written to the parameter is a valid priority identifier. After applying '[Device]DeviceEventsThreadApplyPriority', the application can read back the priority value to verify if it was properly applied.
Note that when opening the device, the GHACHI Producer attempts itself to elevate the thread priority to a suitable value.
The feature is not available for devices not supporting device events or if the event handling was disabled using the 'device_event_handling=0' generic parameter.
BEWARE: Setting this parameter can lead to an unusable or poorly performing system, use with care.
'[Device]DeviceEventsThreadSchedulingPolicy' <scheduling_policy> integer pre-defined OS-specific scheduling policy value to be used for the internal event processing thread. The actual values are directly the priority identifiers of the operating system, e.g. SCHED_FIFO under Linux. Note that this feature is not available under Windows.
The actual scheduling policy is applied only after executing the '[Device]DeviceEventsThreadApplyPriority' command parameter, together with the '[Device]DeviceEventsThreadPriority' value.
It is the responsibility of the application to ensure that the calling process has sufficient privileges to apply the scheduling policy and that the value written to the parameter is a valid scheduling policy identifier. After applying '[Device]DeviceEventsThreadApplyPriority', the application can read back the scheduling policy value to verify if it was properly applied.
The feature is not available for devices not supporting device events or if the event handling was disabled using the 'device_event_handling=0' generic parameter.
BEWARE: Setting this parameter can lead to an unusable or poorly performing system, use with care.
'[Stream]StreamBufferHandlingMode' 'OldestFirst', 'OldestFirstOverwrite', 'NewestOnly' 'OldestFirst' string pre-defined Selects the mode the streaming engine uses to handle newly acquired data, in particular when the camera runs faster than the application processing. The parameter is writeable only if no acquisition is active. Supported values are:
  • 'OldestFirst': The acquired buffers are always delivered in FIFO manner (oldest first). If the acquisition engine receives a new buffer from the camera but has no available free buffer to fill it in, the new data is discarded.
  • 'OldestFirstOverwrite': The acquired buffers are always delivered in FIFO manner (oldest first). If the acquisition engine receives a new buffer from the camera but has no available free buffer to fill it in, it checks, whether there are older buffers waiting for delivery, not yet picked up by the Consumer. If yes, it takes the oldest of them, overwrites it with the new data and appends it to the end of the output queue. If the output queue is empty (no buffer available for overwriting), the new data is discarded. Applicable for socket driver only, undefined behavior with filter driver.
  • 'NewestOnly': The output queue of buffers waiting for delivery never contains more than a single (newest) buffer. If the acquisition engine receives a new buffer and there is already an older buffer waiting for delivery in the output queue, the new buffer is put to the output queue instead and the old one is reused for next acquisition. If there are no available free buffers and the output queue is also empty, new data is discarded.
'[Stream]StreamThreadPriority' <thread_priority> integer pre-defined OS-specific thread priority value to be used for the internal stream processing thread. The actual values are directly the priority identifiers of the operating system, e.g. THREAD_PRIORITY_HIGHEST under Windows or a real-time priority value under Linux.
The actual priority is applied only after executing the '[Stream]StreamThreadApplyPriority' command parameter, possibly together with the '[Stream]StreamThreadSchedulingPolicy' value if applicable on given system.
It is the responsibility of the application to ensure that the calling process has sufficient privileges to apply the priority change and that the value written to the parameter is a valid priority identifier. After applying '[Stream]StreamThreadApplyPriority', the application can read back the priority value to verify if it was properly applied.
Note that when opening the device, the GHACHI Producer attempts itself to elevate the thread priority to a suitable value.
BEWARE: Setting this parameter can lead to an unusable or poorly performing system, use with care.
'[Stream]StreamThreadSchedulingPolicy' <scheduling_policy> integer pre-defined OS-specific scheduling policy value to be used for the internal stream processing thread. The actual values are directly the priority identifiers of the operating system, e.g. SCHED_FIFO under Linux. Note that this feature is not available under Windows.
The actual scheduling policy is applied only after executing the '[Stream]StreamThreadApplyPriority' command parameter, together with the '[Stream]StreamThreadPriority' value.
It is the responsibility of the application to ensure that the calling process has sufficient privileges to apply the scheduling policy and that the value written to the parameter is a valid scheduling policy identifier. After applying '[Stream]StreamThreadApplyPriority', the application can read back the scheduling policy value to verify if it was properly applied.
BEWARE: Setting this parameter can lead to an unusable or poorly performing system, use with care.
'add_objectmodel3d_overlay_attrib' 'disable', 'enable' 'disable' string pre-defined Controls if the acquisition interface should attempt to append the intensity/color overlay to the generated 3D object models. Applicable only if a 3D object model is being output from given grab operator. When switched on, the acquisition interface will try to find suitable information within the acquired data (if it is provided by the device). If so, it appends the overlay information for each point in the output model in form of an extended attribute. Note that in some advanced use cases there might be multiple potential overlay images output by the device, the acquisition interface therefore attempts to find the most suitable one.
First, it tries to identify data marked as "intensity" image in the acquired data. If found and provided as monochrome 2D image, it is appended as '&intensity_gray' extended attribute. If found and provided as RGB image, it is appended as three extended attributes, '&intensity_red', '&intensity_green' and '&intensity_blue'.
If "intensity" data cannot be identified, it tries to find data marked as "reflectance". If found and provided as monochrome 2D image, it is appended as '&reflectance_gray' extended attribute. If found and provided as RGB image, it is appended as three extended attributes, '&reflectance_red', '&reflectance_green' and '&reflectance_blue'.
Finally, if neither "intensity" nor "reflectance" data can be identified (either not present or not correctly marked by the device, it picks the first 2D image within the acquired data than can be mapped to the 3D coordinates. If found and provided as monochrome 2D image, it is appended as '&overlay_gray' extended attribute. If found and provided as RGB image, it is appended as three extended attributes, '&overlay_red', '&overlay_green' and '&overlay_blue'.
If no suitable 2D image is found, no overlay is appended. The actually appended extended attributes can be queried for example using the get_object_model_3d_params operator with the 'extended_attribute_names' parameter. The overlay can be also used for visualization purposes.
'available_callback_types' ['<callback_types>'] string dynamic Returns a list containing all parameters, for which a callback can be registered. This includes all parameters published by the device and GHACHI Producer via the GenICam interface, including those temporarily unavailable, because availability change might be coupled with the callback.
'available_param_names' ['<names>'] string dynamic Returns a list containing all available parameters, i.e. those used by the HALCON GStreamer image acquisition interface and those published by the device and GHACHI Producer via the GenICam interface (see parameter naming conventions). Note that availability of some parameters might depend on acquisition status, values of other parameters or other conditions, so the list dynamically changes during runtime.
'bits_per_channel' -1, 8, 10, 12, 14, 16 -1 integer pre-defined Number of bits per channel of the resulting HALCON image. In case of -1 the bit depth of each respective acquired buffer is used. By specifying a value greater than 8 the grabbed images are delivered as uint2 images.
'buffer_frameid' <frame_id> integer dynamic Frame ID attached to the last grabbed (image) buffer by the device (or GHACHI Producer). Typically sequentially incremented number of the frame. Skipped ID's in the sequence could indicate that one or more frames was dropped in the device or GHACHI Producer, for example due to acquisition engine overflow reasons. Note that on 32-bit systems only the lower 32-bit part of up to 64-bit timestamp is delivered (unless 'split_param_values_into_dwords' parameter is enabled). See acquisition buffer handling.
'buffer_is_incomplete' 0, 1 integer dynamic Shows if the last grabbed image is incomplete (e.g. due to lost packets). See acquisition buffer handling.
'buffer_reallocation_mode' 'only_increase_size', 'follow_payloadsize' 'only_increase_size' string pre-defined Defines the strategy to follow when reallocating the buffers for a new acquisition. In case of 'only_increase_size', the buffers will be only reallocated when the payload size increases. In case of 'follow_payloadsize', the buffers will be reallocated every time the payload size changes.
'buffer_timestamp' <timestamp> integer dynamic Timestamp attached to the last grabbed (image) buffer by the device (or GHACHI Producer). The unit and actual meaning of the timestamp (when it is generated) is device specific. If the frequency of the timestamp counter is known, the value in nanoseconds can be read from 'buffer_timestamp_ns'. Note that on 32-bit systems only the lower 32-bit part of up to 64-bit timestamp is delivered (unless 'split_param_values_into_dwords' parameter is enabled). See acquisition buffer handling.
'buffer_timestamp_ns' <timestamp> integer dynamic Timestamp attached to the last grabbed (image) buffer by the device (or GHACHI Producer). The value is in nanoseconds, but might not be available if the timestamp frequency is unknown (refer also to 'buffer_timestamp' and 'device_timestamp_frequency'). Note that on 32-bit systems only the lower 32-bit part of up to 64-bit timestamp is delivered (unless 'split_param_values_into_dwords' parameter is enabled). See acquisition buffer handling.
'camera_type' 'default', <ini/xml filename> 'default' string pre-defined Returns the path to the configuration file used for the CameraType parameter in open_framegrabber.
'clear_buffer' 'disable', 'enable' 'disable' string pre-defined If enabled, each buffer content is cleared before re-queueing (all bytes set to 0xF0 regardless the expected pixel format), so you can see which parts of an image are missing, in case e.g. the transfer of some image packets failed. This parameter adds of course a runtime overhead to write the 0xF0 data every time a buffer is queued. It is mainly useful for debugging in combination with transport layers which do not guarantee the transfer of complete images. Please note, that this parameter does not modify the buffer queue, only the content of a buffer will be set to a defined state.
'color_space' 'default', 'gray', 'raw', 'rgb', 'yuv' 'default' string pre-defined Returns the current color space.
'confidence_mode' 'off', 'object_model_3d' 'off' string pre-defined Controls if (and how) the information about pixel confidence level is used by the acquisition interface. Applicable only for devices and use cases where the confidence information is delivered (per-pixel) together with the actual pixel data.
The threshold to distinguish between valid and invalid pixels is controlled using the 'confidence_threshold' parameter.
Note that in some use cases there might be other criteria how to mark given pixel invalid, for example if the device uses "invalid pixel value" for a 3D coordinate. These cases are not covered by the 'confidence_mode' parameter and such invalid pixels are always rejected from the 3D object model. Possible values are:
  • off: Default value. The pixel confidence information is not applied to any of the grab operator outputs, even if supplied by the device.
  • object_model_3d: If the pixel confidence level information is available, it is applied to the eventually generated 3D object models (but not to any other outputs, in particular not to the image outputs). This means that pixels ("points") with confidence lower than the configured threshold are not included in the generated 3D object model.
'confidence_threshold' [0.0, 1.0] 0.5 float pre-defined Threshold separating between valid and invalid pixels. Applicable only for devices and use cases where the confidence information is delivered (per-pixel) together with the actual pixel data. The decision how (to which outputs) the confidence threshold is applied is controlled using the 'confidence_mode' parameter.
The threshold is interpreted as a (float) ratio between 0.0 and 1.0. The acquisition interface will remap this ratio to the actual confidence range provided by the device and use it to decide which pixels are valid and which not. Pixels with confidence lower than the specified threshold are considered invalid.
'coordinate_transform_mode' 'none', 'cartesian', 'reference' 'reference' string pre-defined Controls which coordinate transformation operations should the acquisition interface attempt to perform when building the 3D object model from acquired 3D coordinates. Note that the decision which transformation should be performed and which parameters should be used fully depends on the 3D configuration information provided by the device together with the acquired data. If this information is insufficient or coordinates are inaccurate, the result of the transformation(s) might be meaningless or unpredictable. Refer to for more details.
Possible values are:
  • none: The acquisition interface will not perform any coordinate transformation. The 3D object model will contain the "raw" coordinates, possibly only scaled depending on the hints from the device.
  • cartesian: If the coordinate system used by the device is other than Cartesian, the acquisition interface will convert the coordinates to Cartesian system (native for HALCON's 3D object model). It will not attempt to further transform the coordinates from the device's internal ("anchor") coordinate system to the reference system.
  • reference: Default mode. Will transform to Cartesian coordinates if needed and then attempt to transform to the "reference" coordinate system if the device supports it and provides corresponding instructions. The purpose of the reference system is to allow merging and aligning data from multiple devices. The reference system is in contrast with the native ("anchor") coordinate system which is device specific and corresponds to its actual measurement system and actual configuration.
    The position and orientation of the reference system should be indicated by a reference point marker on the device's housing.
    This always directly implies the transformation to Cartesian coordinates because the reference coordinate system is always Cartesian.
'create_objectmodel3d' 'disable', 'enable' 'disable' string pre-defined Controls whether the acquisition interface should attempt to generate HALCON 3D object model(s) when encountering 3D coordinates within the acquired data.
To obtain a 3D object model, the application has to use the grab_data/grab_data_async operators which can return the handles to the generated models through the control data outputs. The grab_image/grab_image_async operators cannot return the 3D object models.
IMPORTANT: the parameter is disabled by default. When enabling, the application is responsible for releasing the generated object models and associated resources using the clear_object_model_3d operator once it does not need given model(s) any more. It should do so by tracking which of the control data outputs of every single grab_data/grab_data_async calls carry 3D object model handle(s). This can be done using the 'data_contents' parameter.
When generating the 3D object model, the acquisition interface processes the 3D coordinates found in the acquired data and builds the point cloud with help of the information about the actual 3D configuration reported by the device. Refer to for more details.
'data_contents' 'unknown', 'object_model_3d', 'text_report' 0 string pre-defined Tuple describing logical type of the control data outputs returned by the last grab operator. Not applicable if last successful grab was performed through grab_image/grab_image_async. In case of grab_data/grab_data_async it returns tuple of the size corresponding to the number of control data values returned through those operators. Possible values are:
  • unknown: The logical type of the data could not be identified.
  • object_model_3d: Integer representing a handle of the 3D object model generated from the acquired data. IMPORTANT: the model has to be released (clear_object_model_3d) when no more used, otherwise the associated resources will be leaking. The generation of the 3D object models is controlled using 'create_objectmodel3d' parameter (disabled by default). Beware that in special use cases more than one object models can be generated.
  • text_report: Might be used for internal purposes and during support cases. Should be ignored by all applications.
'data_purpose_id' --- 0xFFFFFFFFFFFFFFFF integer pre-defined Tuple of integer values allowing to track data purpose IDs associated to individual control data outputs returned by the last grab operator. Intended for advanced use cases when the data should be matched with the device configuration. The use of the parameter is application specific and requires knowledge of the GenICam SFNC data model and specific device. Not applicable if last successful grab was performed through grab_image/grab_image_async. In case of grab_data/grab_data_async it returns tuple of the size corresponding to the number of control data values returned through those operators. If the ID could not be identified (e.g. because the underlying communication protocol does not provide such information), invalid value will be returned (max value of given integer range).
'data_region_id' --- 0xFFFFFFFFFFFFFFFF integer pre-defined Tuple of integer values allowing to track region IDs associated to individual control data outputs returned by the last grab operator. Intended for advanced use cases when the data should be matched with the device configuration. The use of the parameter is application specific and requires knowledge of the GenICam SFNC data model and specific device. Not applicable if last successful grab was performed through grab_image/grab_image_async. In case of grab_data/grab_data_async it returns tuple of the size corresponding to the number of control data values returned through those operators. If the ID could not be identified (e.g. because the underlying communication protocol does not provide such information), invalid value will be returned (max value of given integer range).
'data_source_id' --- 0xFFFFFFFFFFFFFFFF integer pre-defined Tuple of integer values allowing to track source IDs associated to individual control data outputs returned by the last grab operator. Intended for advanced use cases when the data should be matched with the device configuration. The use of the parameter is application specific and requires knowledge of the GenICam SFNC data model and specific device. Not applicable if last successful grab was performed through grab_image/grab_image_async. In case of grab_data/grab_data_async it returns tuple of the size corresponding to the number of control data values returned through those operators. If the ID could not be identified (e.g. because the underlying communication protocol does not provide such information), invalid value will be returned (max value of given integer range).
'delay_after_stop' <milliseconds> 0 integer pre-defined The time to wait (in milliseconds) between stopping the acquisition on the device (AcquisitionStop command) and GHACHI Producer.
'device' ' | device:<device id> | unique_name:<unique name> | user_name:<user-defined name> | interface:<interface id> | producer:Ghachi', '<device id>' string dynamic Returns the Device parameter string used when opening the device (open_framegrabber).
'device_event_handling' 0, 1 1 integer pre-defined Value of the device_event_handling generic parameter specified in open_framegrabber. The device_event_handling is by default switched on for devices with event delivery (message channel) support and off for devices without the event capability. The generic parameter device_event_handling explicitly allows switching the event handling functionality off even for devices with event support.
'device_timestamp_frequency' <frequency_hz> integer dynamic Frequency of the timestamp counter of the device, in ticks per second (Hz). The frequency might not be known for all devices. The counter is used for example to attach timestamps to acquired buffers. Note that on 32-bit systems only the lower 32-bit part of up to 64-bit timestamp is delivered (unless 'split_param_values_into_dwords' parameter is enabled).
'DropBuffers' 0, 1 1 integer pre-defined Controls the behavior when the buffer queue is filled in the appsink element.
'event_data' '<genicam_feature>' string pre-defined Selects GenICam features to be added to the message queue specified by 'event_message_queue' and 'event_selector'. Features can be added individually or as a tuple. To remove individual features, prepend them with a '~'. To clear all currently added features, call set_framegrabber_param(..., 'event_data', []). Read more about the usage of this mechanism at Event Message Queues.
'event_message_queue' 0, '<queue_handle>' handle pre-defined Selects a message queue to which the acquisition interface should send Feature Change Notifications. The corresponding GenICam feature needs to be previously specified by 'event_selector'. Read more about the usage of this mechanism at Event Message Queues.
'event_notification_helper' 'disable', 'enable' 'disable' string pre-defined Controls if the acquisition interface should attempt to automatically (un)set 'EventNotification' during set_framegrabber_callback if the callback is being (un)registered on an SFNC-compliant event. Note that this will only work if the callback is being registered on the actual event feature (e.g. 'EventExposureEnd'), not on one of the event data features (e.g. 'EventExposureEndTimestamp'). For further information on events, see Event Data.
'event_selector' '<genicam_feature>' string pre-defined Selects a GenICam feature for which the acquisition interface should send Feature Change Notifications. They are sent to the message queue specified by 'event_message_queue'. Read more about the usage of this mechanism at Event Message Queues.
'external_trigger' 'false', 'true' 'false' string pre-defined Status of the external trigger.
'field' '<default>' 'progressive' string pre-defined The value is not used, so a default value is returned.
'generic' '', ['num_buffers=<num>', 'workarounds=<list>'], -1 -1 mixed pre-defined Values of the Generic parameter.
'grab_timeout' <milliseconds> 5000 integer pre-defined Current grab timeout in milliseconds.
'GstState' 'Null','Ready','Paused','Playing' string pre-defined Get GStreamer pipeline state.
'horizontal_resolution' 0, 1, resolution 1 integer pre-defined Current value of horizontal resolution.
'image_available' 0, 1 integer dynamic Shows if there is currently an image waiting for delivery by the GHACHI Producer.
'image_contents' 'unknown', 'image', 'coord_a', 'coord_b', 'coord_c', 'coord_mixed', 'confidence' 0 string pre-defined Tuple describing logical type of the image data returned by the last grab operator. If the last successful grab was performed through grab_image/grab_image_async, the parameter returns always single value. In case of grab_data/grab_data_async it returns tuple of the size corresponding to the number of images returned through those operators. Possible values are:
  • unknown: The logical type of the image could not be identified, typically this means some kind of custom, possibly raw data.
  • image: A regular 2D image. The format of the generated HALCON image is affected by the parameters 'bits_per_channel' and 'color_space' if used.
  • coord_a: The output HALCON image contains data corresponding to the 3D "coordinate A" according to the GenICam 3D model. The interpretation of the coordinate depends on the coordinate system used by the device: X for Cartesian, theta for spherical and theta for cylindrical coordinates (refer to GenICam SFNC standard for further details). The data are provided without any conversion, ignoring the 'bits_per_channel' and 'color_space' parameters.
  • coord_b: The output HALCON image contains data corresponding to the 3D "coordinate B" according to the GenICam 3D model. The interpretation of the coordinate depends on the coordinate system used by the device: Y for Cartesian, phi for spherical and Y for cylindrical coordinates (refer to GenICam SFNC standard for further details). The data are provided without any conversion, ignoring the 'bits_per_channel' and 'color_space' parameters.
  • coord_c: The output HALCON image contains data corresponding to the 3D "coordinate C" according to the GenICam 3D model. The interpretation of the coordinate depends on the coordinate system used by the device: Z for Cartesian, rho for spherical and rho for cylindrical coordinates (refer to GenICam SFNC standard for further details). The data are provided without any conversion, ignoring the 'bits_per_channel' and 'color_space' parameters.
  • coord_mixed: Used when the data is recognized as 3D coordinates but the format is unknown. In this case the data are output in the HALCON image "as is" without any transformations, the application has to know how to treat the custom data format. The data are provided without any conversion, ignoring the 'bits_per_channel' and 'color_space' parameters.
  • confidence: The output HALCON image contains data corresponding to the pixel confidence, which expresses the level of validity of corresponding pixel. The interpretation depends on the actual underlying pixel format used by the device to represent confidence (refer to GenICam SFNC standard for further details). The data are provided without any conversion, ignoring the 'bits_per_channel' and 'color_space' parameters.
'image_height' <height> 0 integer pre-defined Height of the last acquired image. See acquisition buffer handling. If there is no valid last buffer available, the last queried value of the 'Height' parameter of the remote device is returned.
'image_pixel_format' --- 0 integer pre-defined Tuple of integer values representing the ID of the original pixel formats of the source data used to generate individual image outputs. This is typically the PFNC 32-bit ID of given pixel format - if unknown or if the data used to generate given image output is not naturally an image, zero will be reported. If the source data is a multi-component image (such as RGB or multi-component 3D coordinate format), the original multi-component pixel format is reported, no matter if all of the components were used to generate given image output (such as an RGB image) or if the image output reflects only one of the components (such as individual 3D coordinate planes, output as separate HALCON images). The original multi-component pixel format might be planar format or not. Note that the color space and bit depth of the actual HALCON image might significantly differ from the source format if the user requests color space conversion through the 'bits_per_channel' and 'color_space' parameters.
'image_purpose_id' --- 0xFFFFFFFFFFFFFFFF integer pre-defined Tuple of integer values allowing to track data purpose IDs associated to individual image outputs returned by the last grab operator. Intended for advanced use cases when the data should be matched with the device configuration. The use of the parameter is application specific and requires knowledge of the GenICam SFNC data model and specific device. If the last successful grab was performed through grab_image/grab_image_async, the parameter returns always single value. In case of grab_data/grab_data_async it returns tuple of the size corresponding to the number of images returned through those operators. If the ID could not be identified (e.g. because the underlying communication protocol does not provide such information), invalid value will be returned (max value of given integer range).
'image_raw_buffer_padding_bytes' --- 0 integer pre-defined Tuple of integers reporting for raw buffers of type 'blob' (see 'image_raw_buffer_type') the size of unused padding bytes at the end of such grabbed HALCON image. Because artificial dimensions need to be chosen for the resulting HALCON image in this case, the size of such image might not exactly equal the size of the buffer data and thus the padding might be needed. Zero is reported for buffers of type 'image'. Applies only in case of the 'raw' color format. See raw output format chapter. If the last successful grab was performed through grab_image/grab_image_async, the parameter returns always single value. In case of grab_data/grab_data_async it returns tuple of the size corresponding to the number of images returned through those operators.
'image_raw_buffer_type' 'image', 'blob' 0 string pre-defined Tuple of strings showing whether the last grabbed HALCON image(s) is created from buffer containing real image data with known properties (in particular image size and pixel format) or if it is created from a blob of other data (non-image data or image data of unknown format). Note that in case of the blob data the dimensions of the HALCON image are meaningless. Applies mainly in case of the 'raw' color format. Possible values are 'image' and 'blob'. See raw output format chapter. If the last successful grab was performed through grab_image/grab_image_async, the parameter returns always single value. In case of grab_data/grab_data_async it returns tuple of the size corresponding to the number of images returned through those operators.
'image_region_id' --- 0xFFFFFFFFFFFFFFFF integer pre-defined Tuple of integer values allowing to track region IDs associated to individual image outputs returned by the last grab operator. Intended for advanced use cases when the data should be matched with the device configuration. The use of the parameter is application specific and requires knowledge of the GenICam SFNC data model and specific device. If the last successful grab was performed through grab_image/grab_image_async, the parameter returns always single value. In case of grab_data/grab_data_async it returns tuple of the size corresponding to the number of images returned through those operators. If the ID could not be identified (e.g. because the underlying communication protocol does not provide such information), invalid value will be returned (max value of given integer range).
'image_source_id' --- 0xFFFFFFFFFFFFFFFF integer pre-defined Tuple of integer values allowing to track source IDs associated to individual image outputs returned by the last grab operator. Intended for advanced use cases when the data should be matched with the device configuration. The use of the parameter is application specific and requires knowledge of the GenICam SFNC data model and specific device. If the last successful grab was performed through grab_image/grab_image_async, the parameter returns always single value. In case of grab_data/grab_data_async it returns tuple of the size corresponding to the number of images returned through those operators. If the ID could not be identified (e.g. because the underlying communication protocol does not provide such information), invalid value will be returned (max value of given integer range).
'image_width' <width> 0 integer pre-defined Width of the last acquired image. See acquisition buffer handling. If there is no valid last buffer available, the last queried value of the 'Width' parameter of the remote device is returned.
'line_in' <default> 0 integer pre-defined The value is not used, so a default value is returned.
'MaxBuffers' 1 integer pre-defined The maximum number of buffers (max-buffers) to queue in the appsink element (0 = unlimited).
'name' 'GStreamer' string pre-defined Name of the HALCON interface.
'num_buffers' <number> 4 integer pre-defined Number of buffers used for the image acquisition.
'num_buffers_await_delivery' <number> integer dynamic Number of (image) buffers waiting for delivery by the GHACHI Producer.
'num_buffers_underrun' <number> integer dynamic Number of lost buffers due to buffer queue underrun since opening the device. Queue underrun occurs when the GHACHI Producer has a new image data available, but it has no free buffer to store them.
'PipelineString' '<pipeline>' string pre-defined Pipeline string using the gst-launch-1.0 syntax. The appsink plugin must be set at the end of the pipeline string.
'port' <port> -1 integer pre-defined The value is not used, so a default value is returned.
'register_<addr>_<len>' integer pre-defined Direct register access for reading and writing integers. The value has to be hexadecimal, e.g. 0x0938. Note that only 4 or 8 Byte length values are accepted. Caution: This is a dangerous function intended for debugging and special cases. Usually only features in the XML should be used.
'revision' '<revision>' string pre-defined Revision number of the GStreamer interface.
'settings_selector' 'RemoteDevice', 'Stream', 'Device', 'System', 'Interface', 'Consumer' 'RemoteDevice' string pre-defined Selects for which component (set of parameters) the streamable parameters are persisted into a file or restored from a file when using set_framegrabber_param(..., 'do_write_settings', []) and set_framegrabber_param(..., 'do_load_settings', []). Selects among the actual (remote) device, one of the GHACHI Producer modules or the Consumer parameters (internal parameters of GStreamer image acquisition interface). Read more about the usage of this mechanism at Parameters – Persisting Device Status.
'split_param_values_into_dwords' 'disable', 'enable' 'disable' string pre-defined Enables a special mode allowing the treatment of integer parameters as tuple of two 32-bit integers. For compatibility with the single-parameter mode, the first tuple element carries always the low 32-bit part of the value, second element carries the high 32-bit part. It is user's responsibility to combine the two parts correctly. This mode is intended especially to help to overcome the problem of 32-bit HALCON featuring only 32-bit integer parameters but having to face up to 64-bit wide GenICam features. In this mode, the get_framegrabber_param returns always a tuple of two integers, set_framegrabber_param accepts both a single parameter or a tuple. Note that this mode affects only integer parameters and only the GenICam based ones, not the internal parameters of HALCON GStreamer image acquisition interface - with few exceptions, the 'buffer_timestamp', 'buffer_timestamp_ns', 'device_timestamp_frequency' and 'buffer_frameid' internal parameters.
'start_async_after_grab_async' 'disable', 'enable' 'enable' string pre-defined Status of 'start_async_after_grab_async'.
'start_column' <column> 0 integer pre-defined Unsupported, returns always 0.
'start_row' <row> 0 integer pre-defined Unsupported, returns always 0.
'streaming_mode' 0, 1 1 integer pre-defined Value of the streaming_mode generic parameter specified in open_framegrabber. The streaming_mode is by default switched on for devices with streaming support and off for peripheral devices (devices without any data streams). The generic parameter streaming_mode explicitly allows switching the streaming functionality off, even for devices with streaming support.
'vertical_resolution' 0, 1, resolution 1 integer pre-defined Current value of vertical resolution.
'volatile' 'disable', 'enable' 'disable' string pre-defined Current value of the volatile mode.
'workarounds' ['', 'enable_range_validation' ] '' string pre-defined List of workarounds enabled by the 'workarounds' generic parameter in open_framegrabber. Individual workaround names are separated by spaces.

Operator set_framegrabber_lut

Not supported by this interface.

Operator get_framegrabber_lut

Not supported by this interface.

Operator set_framegrabber_callback

This interface supports feature change callbacks via the operators set_framegrabber_callback and get_framegrabber_callback.
The callback can be registered for any GenICam based features, i.e., features published by the device and GHACHI Producer through the GenICam description files. The list of supported callback targets can be queried by calling get_framegrabber_param(..., 'available_callback_types', ...).
One of the important use cases for feature change callbacks is the device event delivery mechanism, see details in event data and feature notifications sections. The 'CallbackType' parameter of set_framegrabber_callback defines the feature for which the callback is registered. It is the same plain feature name as used with set_framegrabber_param, including a possible prefix, such as '[Device]' (refer to the parameter naming convention).
The registered callback function would be called whenever a given feature is potentially changed (including its other properties such as range or access mode). Note that it does not necessarily always mean that the feature actually has a new value. If the callback function is set to NULL, the corresponding callback will be unregistered. Note that the interface keeps just a single registration for every feature, if you attempt to register a new callback for a feature that already had a callback registered, the previous registration will be replaced with the new one.

The signature of the callback function is Herror (__stdcall *HAcqCallback)(void *AcqHandle, void *Context, void *UserContext) and uses the following parameters:

  • AcqHandle: Acquisition handle of the corresponding image acquisition instance.
  • Context: Optional context data of the specific callback. Up to now, this parameter is not used, i.e., Context is set to NULL.
  • UserContext: Optional context data of the specific callback. Up to now, this parameter is not used, i.e., UserContext is set to NULL.

Note that the execution time of a user-specific callback function must always be as short as possible since during the execution of a callback function the handling of further internal callbacks might be blocked. This can be achieved by removing the current processing from the user-specific callback function to a separate thread that is controlled via signals or events. The callback function is executed in the context of the underlying interface or driver.

Operator get_framegrabber_callback

This interface supports feature callbacks via the operators set_framegrabber_callback and get_framegrabber_callback. For more information see set_framegrabber_callback.

Operator grab_image_start

Starts a new asynchronous grab. See also grab_image_start and section about acquisition control. Note that this operator starts acquisition on the GHACHI Producer and device and locks features protected during acquisition. If grab_image_start is called repeatedly, the acquisition is restarted on both GHACHI Producer and device. That means, that the buffer queue and all stream related statistics parameters like 'buffer_frameid' are reset. The acquisition can be stopped (and the features unlocked) using set_framegrabber_param(..., 'do_abort_grab', ...).

Operator grab_image

grab_image starts a new synchronous grab of a single image. See also grab_image, section about acquisition control and about grab operators. Note that the interface converts the acquired image to the desired image format specified by the parameters 'bits_per_channel' and 'color_space'.

Operator grab_image_async

grab_image_async returns a single image and starts the next asynchronous grab. See also grab_image_async, section about acquisition control and about grab operators. Note that the interface converts the acquired image to the desired image format specified by the parameters 'bits_per_channel' and 'color_space'.
The 'MaxDelay' parameter of the grab_image_async operator is ignored by the HALCON GStreamer acquisition interface, because there is no way to support it reliably . If needed, the application needs to implement alternative functionality on its own.

Operator grab_data

grab_data starts a new synchronous grab, resulting possibly in tuple of output images and tuple of data outputs of various kind, depending on the input and configuration. See also grab_data, section about acquisition control and about grab operators. Note that the interface converts the acquired images to the desired image format specified by the parameters 'bits_per_channel' and 'color_space'. The output tuples are described using the 'data_contents', 'image_contents' and related parameters.

Operator grab_data_async

grab_data_async returns acquired images/data and starts the next asynchronous grab. See also grab_data_async, section about acquisition control and about grab operators. Note that the interface converts the acquired image to the desired image format specified by the parameters 'bits_per_channel' and 'color_space'. The output tuples are described using the 'data_contents', 'image_contents' and related parameters.
The 'MaxDelay' parameter of the grab_image_async operator is ignored by the HALCON GStreamer acquisition interface, because there is no way to support it reliably . If needed, the application needs to implement alternative functionality on its own.

Operator close_framegrabber

This operator closes the device. See also close_framegrabber.

HDevelop Examples

For this interface there are the following examples available:
  • gstreamer_2pipelines.hdev - A simple example to show how to grab images from two different sources.
  • gstreamer_acquisition_events.hdev - Example how to handle events with additional event data using message queues.
  • gstreamer_frame_rate.hdev - Example to measure the effective frame rate of an acquisition device.
  • gstreamer_nvidia_arguscamera_simple.hdev - A simple example to show how to build a pipeline for nvidia nvarguscamerasrc plugin.
  • gstreamer_parameter_persistence.hdev - Demonstrates writing parameter values to files and restoring parameter values from files.
  • gstreamer_simple.hdev - A simple example to show the usage of the interface.

Release Notes

  • Revision 18.11.4 (Feb 15, 2021):
    • The underlying GenApi version has been updated to the latest official release 3.3.
    • The GenICam caching mechanism was inactive unless one of the environment variables TEMP, TMP or TMPDIR was set. Now, /tmp or HALCONROOT are used as a fallback.
    • The HDevelop example gstreamer_frame_rate.hdev has been added to measure the frame rate of an acquisition device.
    • The HDevelop example gstreamer_acquisition_events.hdev ran into a deadlock in case of very quickly incoming events. This problem has been fixed.
    • The error handling has been improved. Additional information about the cause of an error can now be queried with the operator get_extended_error_info. For the HALCON language interfaces (C# and C++), the HALCON exception class provides methods to access the additional error information.
  • Revision 18.11.3 (Oct 27, 2020):
    • This interface couldn't be loaded from .NET Core applications on Linux and macOS. This problem has been fixed.
    • Added support for 'UYVY' and 'IYU1' pixel formats.
  • Revision 13.0.2 (Sep 18, 2020):
    • Most file operations did not support UTF-8 file names. This problem has been fixed. However, some of the operations like are managed by GenICam GenApi which might not support them.
    • 'do_write_configuration' has been extended to also generate a persistence file for the GenTL Consumer (persisting internal parameters of the HALCON GStreamer image acquisition interface itself like 'grab_timeout'), see Parameters – Persisting Device Status.
    • It is now possible to write and load persistence files for individual GenTL Producer modules or the GenTL Consumer when the device has already been opened. This was so far only possible for the remote device. The persistence file to be written or loaded is selected with the parameter 'settings_selector'.
    • When loading persistence files with open_framegrabber, some of the persisted parameter values were overwritten. This problem has been fixed.
    • The HDevelop example gstreamer_parameter_persistence.hdev has been added to demonstrate writing parameter values to files and restoring parameter values from files.
    • The parameter 'available_event_names' was wrongly written as 'available_event_types'. This problem has been fixed.
  • Revision 13.0.1 (Feb 28, 2020):
    • First official release.