robinson_dirrobinson_dirrobinson_dirRobinsonDirRobinsonDir (Operator)

Name

robinson_dirrobinson_dirrobinson_dirRobinsonDirRobinsonDir — Detect edges (amplitude and direction) using the Robinson operator.

Signature

Description

robinson_dirrobinson_dirrobinson_dirRobinsonDirRobinsonDir calculates an approximation of the first derivative of the image data and is used as an edge detector. In robinson_amprobinson_amprobinson_ampRobinsonAmpRobinsonAmp the following four of the originally proposed eight 3x3 filter masks are convolved with the image. The other four masks are obtained by a multiplication by -1. All masks contain only the values 0,1,-1,2,-2.

     -1   0   1                2   1   0
     -2   0   2                1   0  -1
     -1   0   1                0  -1  -2

      0   1   2                1   2   1
     -1   0   1                0   0   0
     -2  -1   0               -1  -2  -1

The result image contains the maximum response of all masks. The edge directions are returned in ImageEdgeDirImageEdgeDirImageEdgeDirImageEdgeDirimageEdgeDir, and are stored as x / 2. They correspond to the direction of the mask yielding the maximum response.

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.
• Automatically parallelized on channel level.
• Automatically parallelized on domain level.

Parameters

read_image(Image,'fabrik')
robinson_dir(Image,Robinson_dirA,Robinson_dirD)
threshold(Robinson_dirA,Res,128,255)

read_image(&Image,"fabrik");
robinson_dir(Image,&Robinson_dirA,&Robinson_dirD);
threshold(Robinson_dirA,&Res,128,255);

read_image(Image,'fabrik')
robinson_dir(Image,Robinson_dirA,Robinson_dirD)
threshold(Robinson_dirA,Res,128,255)

read_image(Image,'fabrik')
robinson_dir(Image,Robinson_dirA,Robinson_dirD)
threshold(Robinson_dirA,Res,128,255)

read_image(Image,'fabrik')
robinson_dir(Image,Robinson_dirA,Robinson_dirD)
threshold(Robinson_dirA,Res,128,255)

Result

robinson_dirrobinson_dirrobinson_dirRobinsonDirRobinsonDir always returns 2 (H_MSG_TRUE). If the input is empty the behaviour can be set via 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>). If necessary, an exception is raised.

Possible Predecessors

binomial_filterbinomial_filterbinomial_filterBinomialFilterBinomialFilter, gauss_imagegauss_imagegauss_imageGaussImageGaussImage, sigma_imagesigma_imagesigma_imageSigmaImageSigmaImage, median_imagemedian_imagemedian_imageMedianImageMedianImage, smooth_imagesmooth_imagesmooth_imageSmoothImageSmoothImage

Possible Successors

hysteresis_thresholdhysteresis_thresholdhysteresis_thresholdHysteresisThresholdHysteresisThreshold, thresholdthresholdthresholdThresholdThreshold, gray_skeletongray_skeletongray_skeletonGraySkeletonGraySkeleton, nonmax_suppression_dirnonmax_suppression_dirnonmax_suppression_dirNonmaxSuppressionDirNonmaxSuppressionDir, close_edgesclose_edgesclose_edgesCloseEdgesCloseEdges, close_edges_lengthclose_edges_lengthclose_edges_lengthCloseEdgesLengthCloseEdgesLength

Alternatives

edges_imageedges_imageedges_imageEdgesImageEdgesImage, sobel_dirsobel_dirsobel_dirSobelDirSobelDir, kirsch_dirkirsch_dirkirsch_dirKirschDirKirschDir, prewitt_dirprewitt_dirprewitt_dirPrewittDirPrewittDir, frei_dirfrei_dirfrei_dirFreiDirFreiDir

See also

bandpass_imagebandpass_imagebandpass_imageBandpassImageBandpassImage, laplace_of_gausslaplace_of_gausslaplace_of_gaussLaplaceOfGaussLaplaceOfGauss

Module

Foundation