dual_rankdual_rankDualRankDualRankdual_rank (Operator)

Name

dual_rankdual_rankDualRankDualRankdual_rank — Opening, Median and Closing with circle or rectangle mask.

Signature

Description

The operator dual_rankdual_rankDualRankDualRankdual_rank carries out a non-linear transformation of the gray values of all input images (ImageImageImageimageimage). Circles or squares can be used as structuring elements. The operator dual_rankdual_rankDualRankDualRankdual_rank effects two consecutive calls of rank_imagerank_imageRankImageRankImagerank_image. At the first call the range gray value is calculated with the indicated range (ModePercentModePercentModePercentmodePercentmode_percent). The result of this calculation is the input of a further call of rank_imagerank_imageRankImageRankImagerank_image, this time using the range value 100-ModePercentModePercentModePercentmodePercentmode_percent.

When filtering different parameters for border treatment (MarginMarginMarginmarginmargin) can be chosen:

gray value

Pixels outside of the image border are assumed to be constant (with the indicated gray value).

'continued'"continued""continued""continued""continued"

Continuation of the gray values at the image border.

'cyclic'"cyclic""cyclic""cyclic""cyclic"

Cyclic continuation at the image borders.

'mirrored'"mirrored""mirrored""mirrored""mirrored"

Reflection of pixels at the image borders.

A range filtering is calculated according to the following scheme: The indicated mask is put over the image to be filtered in such a way that the center of the mask touches all pixels once. For each of these pixels all neighboring pixels covered by the mask are sorted in an ascending sequence corresponding to their gray values. Each sorted sequence of gray values contains the same number of gray values like the mask has image points. The n-th highest element, (= ModePercentModePercentModePercentmodePercentmode_percent, rank values between 0...100 in percent) is selected and set as result gray value in the corresponding result image.

If ModePercentModePercentModePercentmodePercentmode_percent is 0, then the operator equals to the gray value opening (gray_openinggray_openingGrayOpeningGrayOpeninggray_opening). If ModePercentModePercentModePercentmodePercentmode_percent is 50, the operator results in the median filter, which is applied twice (median_imagemedian_imageMedianImageMedianImagemedian_image). The ModePercentModePercentModePercentmodePercentmode_percent 100 in dual_rankdual_rankDualRankDualRankdual_rank means that it calculates the gray value closing (gray_closinggray_closingGrayClosingGrayClosinggray_closing). Choosing parameter values inside this range results in a smooth transformation of these operators.

For an explanation of the concept of smoothing filters see the introduction of chapter Filters / Smoothing.

Attention

Note that filter operators may return unexpected results if an image with a reduced domain is used as input. Please refer to the chapter Filters.

Execution Information

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

Parameters

read_image(Image,'fabrik')
dual_rank(Image,ImageOpening,'circle',10,10,'mirrored')
dev_display(ImageOpening)

read_image(&Image,"fabrik");
dual_rank(Image,&ImageOpening,"circle",10,10,"mirrored");
disp_image(ImageOpening,WindowHandle);

read_image(Image,'fabrik')
dual_rank(Image,ImageOpening,'circle',10,10,'mirrored')
dev_display(ImageOpening)

read_image(Image,'fabrik')
dual_rank(Image,ImageOpening,'circle',10,10,'mirrored')
dev_display(ImageOpening)

Complexity

For each pixel: with F = area of the structuring element.

Result

If the parameter values are correct the operator dual_rankdual_rankDualRankDualRankdual_rank returns the value 2 ( H_MSG_TRUE) . 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>)SetSystem("no_object_result",<Result>)SetSystem("no_object_result",<Result>)set_system("no_object_result",<Result>). If necessary an exception is raised.

Possible Predecessors

read_imageread_imageReadImageReadImageread_image

Possible Successors

thresholdthresholdThresholdThresholdthreshold, dyn_thresholddyn_thresholdDynThresholdDynThresholddyn_threshold, sub_imagesub_imageSubImageSubImagesub_image, regiongrowingregiongrowingRegiongrowingRegiongrowingregiongrowing

Alternatives

rank_imagerank_imageRankImageRankImagerank_image, gray_closinggray_closingGrayClosingGrayClosinggray_closing, gray_openinggray_openingGrayOpeningGrayOpeninggray_opening, median_imagemedian_imageMedianImageMedianImagemedian_image

See also

gen_circlegen_circleGenCircleGenCirclegen_circle, gen_rectangle1gen_rectangle1GenRectangle1GenRectangle1gen_rectangle1, gray_erosion_rectgray_erosion_rectGrayErosionRectGrayErosionRectgray_erosion_rect, gray_dilation_rectgray_dilation_rectGrayDilationRectGrayDilationRectgray_dilation_rect, sigma_imagesigma_imageSigmaImageSigmaImagesigma_image

References

W. Eckstein, O. Munkelt “Extracting Objects from Digital Terrain Model” Remote Sensing and Reconstruction for Threedimensional Objects and Scenes, SPIE Symposium on Optical Science, Engeneering, and Instrumentation, July 1995, San Diego

Module

Foundation