prepare_direct_variation_modelT_prepare_direct_variation_modelPrepareDirectVariationModelPrepareDirectVariationModelprepare_direct_variation_model (Operator)

Name

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

Signature

prepare_direct_variation_model(RefImage, VarImage : : ModelID, AbsThreshold, VarThreshold : )

Description

prepare_direct_variation_modelprepare_direct_variation_modelPrepareDirectVariationModelPrepareDirectVariationModelprepare_direct_variation_model prepares a variation model for the image comparison with compare_variation_modelcompare_variation_modelCompareVariationModelCompareVariationModelcompare_variation_model or compare_ext_variation_modelcompare_ext_variation_modelCompareExtVariationModelCompareExtVariationModelcompare_ext_variation_model. The variation model must have been created with ModeModeModemodemode='direct'"direct""direct""direct""direct" with create_variation_modelcreate_variation_modelCreateVariationModelCreateVariationModelcreate_variation_model. In contrast to prepare_variation_modelprepare_variation_modelPrepareVariationModelPrepareVariationModelprepare_variation_model, the ideal image of the object and the corresponding variation image are not computed with train_variation_modeltrain_variation_modelTrainVariationModelTrainVariationModeltrain_variation_model, but are specified directly in RefImageRefImageRefImagerefImageref_image and VarImageVarImageVarImagevarImagevar_image. This is useful if the variation model should be created from a single image, as described with create_variation_modelcreate_variation_modelCreateVariationModelCreateVariationModelcreate_variation_model. The variation image should typically be created with edge operators like sobel_ampsobel_ampSobelAmpSobelAmpsobel_amp, edges_imageedges_imageEdgesImageEdgesImageedges_image, or gray_range_rectgray_range_rectGrayRangeRectGrayRangeRectgray_range_rect.

prepare_direct_variation_modelprepare_direct_variation_modelPrepareDirectVariationModelPrepareDirectVariationModelprepare_direct_variation_model converts the ideal image RefImageRefImageRefImagerefImageref_image and the variation image VarImageVarImageVarImagevarImagevar_image into two threshold images and stores them in the variation model. These threshold images are used in compare_variation_modelcompare_variation_modelCompareVariationModelCompareVariationModelcompare_variation_model or compare_ext_variation_modelcompare_ext_variation_modelCompareExtVariationModelCompareExtVariationModelcompare_ext_variation_model to perform the comparison of the current image to the variation model.

Two thresholds are used to compute the threshold images. The parameter AbsThresholdAbsThresholdAbsThresholdabsThresholdabs_threshold 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 VarThresholdVarThresholdVarThresholdvarThresholdvar_threshold determines a factor relative to the variation image for the minimum difference of the current image and the ideal image. VarThresholdVarThresholdVarThresholdvarThresholdvar_threshold utilizes VarImageVarImageVarImagevarImagevar_image to define regions, in which differences in gray values may occur which should not be counted as errors. This allows variations for specific parts of the object to inspect. AbsThresholdAbsThresholdAbsThresholdabsThresholdabs_threshold and VarThresholdVarThresholdVarThresholdvarThresholdvar_threshold 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 RefImageRefImageRefImagerefImageref_image, v(x,y) the variation image VarImageVarImageVarImagevarImagevar_image, , , , and (or , , , and , respectively). Then the two threshold images are computed as follows: If the current image c(x,y) is compared to the variation model using compare_variation_modelcompare_variation_modelCompareVariationModelCompareVariationModelcompare_variation_model, the output region contains all points that differ substantially from the model, i.e., that fulfill the following condition: In compare_ext_variation_modelcompare_ext_variation_modelCompareExtVariationModelCompareExtVariationModelcompare_ext_variation_model, 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_modelGetThreshImagesVariationModelGetThreshImagesVariationModelget_thresh_images_variation_model.

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

Execution Information

Multithreading type: reentrant (runs in parallel with non-exclusive operators).
Multithreading scope: global (may be called from any thread).
Processed without parallelization.

This operator modifies the state of the following input parameter:

ModelIDModelIDModelIDmodelIDmodel_id

During execution of this operator, access to the value of this parameter must be synchronized if it is used across multiple threads.

Parameters

RefImageRefImageRefImagerefImageref_image (input_object) singlechannelimage → object (byte / int2 / uint2)

Reference image of the object.

VarImageVarImageVarImagevarImagevar_image (input_object) singlechannelimage → object (byte / int2 / uint2)

Variation image of the object.

ModelIDModelIDModelIDmodelIDmodel_id (input_control, state is modified) variation_model → (handle)

ID of the variation model.

AbsThresholdAbsThresholdAbsThresholdabsThresholdabs_threshold (input_control) number(-array) → (real / integer)

Absolute minimum threshold for the differences between the image and the variation model.

Default: 10

Suggested values: 0, 5, 10, 15, 20, 30, 40, 50

Restriction: AbsThreshold >= 0

VarThresholdVarThresholdVarThresholdvarThresholdvar_threshold (input_control) number(-array) → (real / integer)

Threshold for the differences based on the variation of the variation model.

Default: 2

Suggested values: 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5

Restriction: VarThreshold >= 0

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')

Result

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