prepare_direct_variation_modelprepare_direct_variation_modelprepare_direct_variation_modelPrepareDirectVariationModelPrepareDirectVariationModel (Operator)

Name

prepare_direct_variation_modelprepare_direct_variation_modelprepare_direct_variation_modelPrepareDirectVariationModelPrepareDirectVariationModel — Prepare a variation model for comparison with an image.

Signature

Description

prepare_direct_variation_modelprepare_direct_variation_modelprepare_direct_variation_modelPrepareDirectVariationModelPrepareDirectVariationModel prepares a variation model for the image comparison with compare_variation_modelcompare_variation_modelcompare_variation_modelCompareVariationModelCompareVariationModel or compare_ext_variation_modelcompare_ext_variation_modelcompare_ext_variation_modelCompareExtVariationModelCompareExtVariationModel. The variation model must have been created with Mode='direct'"direct""direct""direct""direct" with create_variation_modelcreate_variation_modelcreate_variation_modelCreateVariationModelCreateVariationModel. In contrast to prepare_variation_modelprepare_variation_modelprepare_variation_modelPrepareVariationModelPrepareVariationModel, the ideal image of the object and the corresponding variation image are not computed with train_variation_modeltrain_variation_modeltrain_variation_modelTrainVariationModelTrainVariationModel, but are specified directly in RefImageRefImageRefImageRefImagerefImage and VarImageVarImageVarImageVarImagevarImage. This is useful if the variation model should be created from a single image, as described with create_variation_modelcreate_variation_modelcreate_variation_modelCreateVariationModelCreateVariationModel. The variation image should typically be created with edge operators like sobel_ampsobel_ampsobel_ampSobelAmpSobelAmp, edges_imageedges_imageedges_imageEdgesImageEdgesImage, or gray_range_rectgray_range_rectgray_range_rectGrayRangeRectGrayRangeRect.

prepare_direct_variation_modelprepare_direct_variation_modelprepare_direct_variation_modelPrepareDirectVariationModelPrepareDirectVariationModel converts the ideal image RefImageRefImageRefImageRefImagerefImage and the variation image VarImageVarImageVarImageVarImagevarImage into two threshold images and stores them in the variation model. These threshold images are used in compare_variation_modelcompare_variation_modelcompare_variation_modelCompareVariationModelCompareVariationModel or compare_ext_variation_modelcompare_ext_variation_modelcompare_ext_variation_modelCompareExtVariationModelCompareExtVariationModel to perform the comparison of the current image to the variation model.

Two thresholds are used to compute the threshold images. The parameter AbsThresholdAbsThresholdAbsThresholdAbsThresholdabsThreshold determines the minimum amount of gray levels by which the image of the current object must differ from the image of the ideal object. The parameter VarThresholdVarThresholdVarThresholdVarThresholdvarThreshold determines a factor relative to the variation image for the minimum difference of the current image and the ideal image. AbsThresholdAbsThresholdAbsThresholdAbsThresholdabsThreshold and VarThresholdVarThresholdVarThresholdVarThresholdvarThreshold each can contain one or two values. If two values are specified, different thresholds can be determined for too bright and too dark pixels. In this mode, the first value refers to too bright pixels, while the second value refers to too dark pixels. If one value is specified, this value refers to both the too bright and too dark pixels. Let i(x,y) be the ideal image RefImageRefImageRefImageRefImagerefImage, v(x,y) the variation image VarImageVarImageVarImageVarImagevarImage, a{u}=AbsThresholdAbsThresholdAbsThresholdAbsThresholdabsThreshold[0], a{l}=AbsThresholdAbsThresholdAbsThresholdAbsThresholdabsThreshold[1], b{u}=VarThresholdVarThresholdVarThresholdVarThresholdvarThreshold[0], and b{l}=VarThresholdVarThresholdVarThresholdVarThresholdvarThreshold[1] (or a{u}=AbsThresholdAbsThresholdAbsThresholdAbsThresholdabsThreshold, a{l}=AbsThresholdAbsThresholdAbsThresholdAbsThresholdabsThreshold, b{u}=VarThresholdVarThresholdVarThresholdVarThresholdvarThreshold, and b{l}=VarThresholdVarThresholdVarThresholdVarThresholdvarThreshold, respectively). Then the two threshold images t{u,l} are computed as follows:

  t{u}(x,y) = i(x,y) + max{a{u},b{u}*v(x,y)}
  t{l}(x,y) = i(x,y) - max{a{l},b{l}*v(x,y)}

If the current image c(x,y) is compared to the variation model using compare_variation_modelcompare_variation_modelcompare_variation_modelCompareVariationModelCompareVariationModel, the output region contains all points that differ substantially from the model, i.e., that fulfill the following condition:

  c(x,y) > t{u}(x,y) or c(x,y) < t{l}(x,y) .

In compare_ext_variation_modelcompare_ext_variation_modelcompare_ext_variation_modelCompareExtVariationModelCompareExtVariationModel, extended comparison modes are available, which return only too bright errors, only too dark errors, or bright and dark errors as separate regions.

After the threshold images have been created they can be read out with get_thresh_images_variation_modelget_thresh_images_variation_modelget_thresh_images_variation_modelGetThreshImagesVariationModelGetThreshImagesVariationModel.

It should be noted that RefImageRefImageRefImageRefImagerefImage and VarImageVarImageVarImageVarImagevarImage are not stored as the ideal and variation images in the model to save memory in the model.

Parallelization

• Multithreading type: exclusive (runs in parallel only with independent operators).
• Multithreading scope: global (may be called from any thread).
• Processed without parallelization.

Parameters

Example (HDevelop)

read_image (Image, 'model')
sobel_amp (Image, VarImage, 'sum_abs', 3)
get_image_pointer1 (Image, Pointer, Type, Width, Height)
create_variation_model (Width, Height, Type, 'direct', ModelID)
prepare_direct_variation_model (Image, VarImage, ModelID, 20, 1)
write_variation_model (ModelID, 'model.var')
clear_variation_model (ModelID)

Result

prepare_direct_variation_modelprepare_direct_variation_modelprepare_direct_variation_modelPrepareDirectVariationModelPrepareDirectVariationModel returns 2 (H_MSG_TRUE) if all parameters are correct.

Possible Predecessors

sobel_ampsobel_ampsobel_ampSobelAmpSobelAmp, edges_imageedges_imageedges_imageEdgesImageEdgesImage, gray_range_rectgray_range_rectgray_range_rectGrayRangeRectGrayRangeRect

Possible Successors

compare_variation_modelcompare_variation_modelcompare_variation_modelCompareVariationModelCompareVariationModel, compare_ext_variation_modelcompare_ext_variation_modelcompare_ext_variation_modelCompareExtVariationModelCompareExtVariationModel, get_thresh_images_variation_modelget_thresh_images_variation_modelget_thresh_images_variation_modelGetThreshImagesVariationModelGetThreshImagesVariationModel, write_variation_modelwrite_variation_modelwrite_variation_modelWriteVariationModelWriteVariationModel

Alternatives

prepare_variation_modelprepare_variation_modelprepare_variation_modelPrepareVariationModelPrepareVariationModel

See also

create_variation_modelcreate_variation_modelcreate_variation_modelCreateVariationModelCreateVariationModel

Module

Matching