HALCON Reference Manual 10.0.2

Table of Contents / Segmentation / Threshold

check_differencecheck_differencecheck_differenceCheckDifferenceCheckDifference (Operator)

Name

check_differencecheck_differencecheck_differenceCheckDifferenceCheckDifference — Compare two images pixel by pixel.

Signature

check_difference(Image, Pattern : Selected : Mode, DiffLowerBound, DiffUpperBound, GrayOffset, AddRow, AddCol : )

Description

check_differencecheck_differencecheck_differenceCheckDifferenceCheckDifference selects from the input image ImageImageImageImageimage those pixels (g_{o} = g_{ImageImageImageImageimage}), whose gray value difference to the corresponding pixels in PatternPatternPatternPatternpattern is inside (outside) of the interval [DiffLowerBoundDiffLowerBoundDiffLowerBoundDiffLowerBounddiffLowerBound,DiffUpperBoundDiffUpperBoundDiffUpperBoundDiffUpperBounddiffUpperBound]. The pixels of PatternPatternPatternPatternpattern are translated by (AddRowAddRowAddRowAddRowaddRow,AddColAddColAddColAddColaddCol) with respect to ImageImageImageImageimage. Let g_{p} be the gray value from PatternPatternPatternPatternpattern translated by (AddRowAddRowAddRowAddRowaddRow,AddColAddColAddColAddColaddCol) with respect to g_{o}.

If the selected mode ModeModeModeModemode is 'diff_inside', a pixel g_{o} is selected if

       g_o - g_p - GrayOffset >= DiffLowerBound   and
       g_o - g_p - GrayOffset <= DiffUpperBound.

If the mode is set to 'diff_outside', a pixel g_{o} is selected if

       g_o - g_p - GrayOffset < DiffLowerBound   or
       g_o - g_p - GrayOffset > DiffUpperBound.

This test is performed for all points of the domain (region) of ImageImageImageImageimage, intersected with the domain of the translated PatternPatternPatternPatternpattern. All points fulfilling the above condition are aggregated in the output region. The two images may be of different size. Typically, PatternPatternPatternPatternpattern is smaller than ImageImageImageImageimage.

Parallelization

Multithreading type: reentrant (runs in parallel with non-exclusive operators).
Multithreading scope: global (may be called from any thread).
Automatically parallelized on tuple level.

Parameters

ImageImageImageImageimage (input_object) image(-array) → object (byte)

Input image.

PatternPatternPatternPatternpattern (input_object) image(-array) → object (byte)

Comparison image.

SelectedSelectedSelectedSelectedselected (output_object) region(-array) → object

Points in which the two images are similar/different.

ModeModeModeModemode (input_control) string → (string)

Mode: return similar or different pixels.

Default value: 'diff_outside' "diff_outside" "diff_outside" "diff_outside" "diff_outside"

Suggested values: 'diff_inside'"diff_inside""diff_inside""diff_inside""diff_inside", 'diff_outside'"diff_outside""diff_outside""diff_outside""diff_outside"

DiffLowerBoundDiffLowerBoundDiffLowerBoundDiffLowerBounddiffLowerBound (input_control) number → (integer)

Lower bound of the tolerated gray value difference.

Default value: -5

Suggested values: 0, -1, -2, -3, -5, -7, -10, -12, -15, -17, -20, -25, -30

Typical range of values: -255 ≤ DiffLowerBound DiffLowerBound DiffLowerBound DiffLowerBound diffLowerBound ≤ 255 (lin)

Minimum increment: 1

Recommended increment: 2

Restriction: (-255 <= DiffLowerBound) && (DiffLowerBound <= 255)

DiffUpperBoundDiffUpperBoundDiffUpperBoundDiffUpperBounddiffUpperBound (input_control) number → (integer)

Upper bound of the tolerated gray value difference.

Default value: 5

Suggested values: 0, 1, 2, 3, 5, 7, 10, 12, 15, 17, 20, 25, 30

Typical range of values: -255 ≤ DiffUpperBound DiffUpperBound DiffUpperBound DiffUpperBound diffUpperBound ≤ 255 (lin)

Minimum increment: 1

Recommended increment: 2

Restriction: (-255 <= DiffUpperBound) && (DiffUpperBound <= 255)

GrayOffsetGrayOffsetGrayOffsetGrayOffsetgrayOffset (input_control) number → (integer)

Offset gray value subtracted from the input image.

Default value: 0

Suggested values: -30, -25, -20, -17, -15, -12, -10, -7, -5, -3, -2, -1, 0, 1, 2, 3, 5, 7, 10, 12, 15, 17, 20, 25, 30

Typical range of values: -255 ≤ GrayOffset GrayOffset GrayOffset GrayOffset grayOffset ≤ 255 (lin)

Minimum increment: 1

Recommended increment: 2

Restriction: (-255 <= GrayOffset) && (GrayOffset <= 255)

AddRowAddRowAddRowAddRowaddRow (input_control) point.y → (integer)

Row coordinate by which the comparison image is translated.

Default value: 0

Suggested values: -200, -100, -20, -10, 0, 10, 20, 100, 200

Typical range of values: -32000 ≤ AddRow AddRow AddRow AddRow addRow ≤ 32000 (lin)

Minimum increment: 1

Recommended increment: 1

AddColAddColAddColAddColaddCol (input_control) point.x → (integer)

Column coordinate by which the comparison image is translated.

Default value: 0

Suggested values: -200, -100, -20, -10, 0, 10, 20, 100, 200

Typical range of values: -32000 ≤ AddCol AddCol AddCol AddCol addCol ≤ 32000 (lin)

Minimum increment: 1

Recommended increment: 1

Complexity

Let A be the number of valid pixels. Then the runtime complexity is O(A).

Result

check_differencecheck_differencecheck_differenceCheckDifferenceCheckDifference returns 2 (H_MSG_TRUE) if all parameters are correct. The behavior with respect to the input images and output regions can be determined by setting the values of the flags 'no_object_result'"no_object_result""no_object_result""no_object_result""no_object_result", 'empty_region_result'"empty_region_result""empty_region_result""empty_region_result""empty_region_result", and 'store_empty_region'"store_empty_region""store_empty_region""store_empty_region""store_empty_region" with set_systemset_systemset_systemSetSystemSetSystem. If necessary, an exception is raised.

Possible Successors

connectionconnectionconnectionConnectionConnection, select_shapeselect_shapeselect_shapeSelectShapeSelectShape, reduce_domainreduce_domainreduce_domainReduceDomainReduceDomain, select_grayselect_grayselect_graySelectGraySelectGray, rank_regionrank_regionrank_regionRankRegionRankRegion, dilation1dilation1dilation1Dilation1Dilation1, openingopeningopeningOpeningOpening

Alternatives

sub_imagesub_imagesub_imageSubImageSubImage, dyn_thresholddyn_thresholddyn_thresholdDynThresholdDynThreshold

Module

Foundation

Table of Contents / Segmentation / Threshold

Operators

HALCON Reference Manual 10.0.2