gray_histoT_gray_histogray_histoGrayHistoGrayHisto (Operator)

Name

gray_histoT_gray_histogray_histoGrayHistoGrayHisto — Calculate the gray value distribution.

Signature

Description

The operator gray_histogray_histogray_histoGrayHistoGrayHisto calculates for the image (ImageImageImageImageimage) within RegionsRegionsRegionsRegionsregions the absolute (AbsoluteHistoAbsoluteHistoAbsoluteHistoAbsoluteHistoabsoluteHisto) and relative (RelativeHistoRelativeHistoRelativeHistoRelativeHistorelativeHisto) histogram of the gray values.

Both histograms are tupels of 256 values, which --- beginning at 0 --- contain the frequencies of the individual gray values of the image.

AbsoluteHistoAbsoluteHistoAbsoluteHistoAbsoluteHistoabsoluteHisto indicates the absolute frequencies of the gray values in integers, and RelativeHistoRelativeHistoRelativeHistoRelativeHistorelativeHisto indicates the relative, i.e. the absolute frequencies divided by the area of the image as floating point numbers.

'real'"real""real""real""real"-, 'int2'"int2""int2""int2""int2"-, 'uint2'"uint2""uint2""uint2""uint2"-, and 'int4'"int4""int4""int4""int4"-images are transformed into 'byte'"byte""byte""byte""byte"-images (first the largest and smallest gray value in the image are determined, and then the original gray values are mapped linearly into the area 0..255) and then processed as mentioned above. The histogram can also be returned directly as a graphic via the operators set_paint(::WindowHandle,'histogram':)set_paint(WindowHandle,"histogram")set_paint(WindowHandle,"histogram")SetPaint(WindowHandle,"histogram")SetPaint(WindowHandle,"histogram") and disp_imagedisp_imagedisp_imageDispImageDispImage.

Attention

Real, int2, uint2, and int4 images are reduced to 256 gray values.

gray_histogray_histogray_histoGrayHistoGrayHisto can be executed on OpenCL devices for byte, int1, directional and cyclic images if the OpenCL device supports the cl_khr_local_int32_base_atomics and cl_khr_global_int32_base_atomics extensions (which are optional in OpenCL 1.0). Unlike most other HALCON operators, gray_histogray_histogray_histoGrayHistoGrayHisto can be substantially slower on an OpenCL device when the domain of the image has been reduced.

OpenCL support is not available in HALCON XL, as 64 bit atomic integer arithmetic would be required.

Parallelization

• Supports OpenCL compute devices.
• Multithreading type: reentrant (runs in parallel with non-exclusive operators).
• Multithreading scope: global (may be called from any thread).
• Automatically parallelized on internal data level.

Parameters

Complexity

If F is the area of the region the runtime complexity is O(F + 255).

Result

The operator gray_histogray_histogray_histoGrayHistoGrayHisto returns the value 2 (H_MSG_TRUE) if the image has defined gray values and the parameters are correct. The behavior in case of empty input (no input images available) is set via the operator set_system(::'no_object_result',<Result>:)set_system("no_object_result",<Result>)set_system("no_object_result",<Result>)SetSystem("no_object_result",<Result>)SetSystem("no_object_result",<Result>), the behavior in case of empty region is set via set_system(::'empty_region_result',<Result>:)set_system("empty_region_result",<Result>)set_system("empty_region_result",<Result>)SetSystem("empty_region_result",<Result>)SetSystem("empty_region_result",<Result>). If necessary an exception is raised.

Possible Successors

histo_to_threshhisto_to_threshhisto_to_threshHistoToThreshHistoToThresh, gen_region_histogen_region_histogen_region_histoGenRegionHistoGenRegionHisto

Alternatives

min_max_graymin_max_graymin_max_grayMinMaxGrayMinMaxGray, intensityintensityintensityIntensityIntensity, gray_histo_absgray_histo_absgray_histo_absGrayHistoAbsGrayHistoAbs, gray_histo_rangegray_histo_rangegray_histo_rangeGrayHistoRangeGrayHistoRange

See also

set_paintset_paintset_paintSetPaintSetPaint, disp_imagedisp_imagedisp_imageDispImageDispImage, histo_2dimhisto_2dimhisto_2dimHisto2dimHisto2dim, scale_image_maxscale_image_maxscale_image_maxScaleImageMaxScaleImageMax, entropy_grayentropy_grayentropy_grayEntropyGrayEntropyGray

Module

Foundation