frei_ampfrei_ampFreiAmpfrei_ampFreiAmpFreiAmp (Operator)

Name

frei_ampfrei_ampFreiAmpfrei_ampFreiAmpFreiAmp — Detect edges (amplitude) using the Frei-Chen operator.

Signature

Description

frei_ampfrei_ampFreiAmpfrei_ampFreiAmpFreiAmp calculates an approximation of the first derivative of the image data and is used as an edge detector. The filter is based on the following filter masks:

  A =
         1       sqrt(2)        1
         0          0           0
        -1      -sqrt(2)       -1

  B =
         1          0          -1
       sqrt(2)      0       -sqrt(2)
         1          0          -1

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.

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')
frei_amp(Image,Frei_amp)
threshold(Frei_amp,Edges,128,255)

read_image(&Image,"fabrik");
frei_amp(Image,&Frei_amp);
threshold(Frei_amp,&Edges,128,255);

read_image(Image,'fabrik')
frei_amp(Image,Frei_amp)
threshold(Frei_amp,Edges,128,255)

read_image(Image,'fabrik')
frei_amp(Image,Frei_amp)
threshold(Frei_amp,Edges,128,255)

read_image(Image,'fabrik')
frei_amp(Image,Frei_amp)
threshold(Frei_amp,Edges,128,255)

read_image(Image,'fabrik')
frei_amp(Image,Frei_amp)
threshold(Frei_amp,Edges,128,255)

Result

frei_ampfrei_ampFreiAmpfrei_ampFreiAmpFreiAmp always returns 2 (H_MSG_TRUE). If the input is empty the behavior can be set via set_system('no_object_result',<Result>)set_system("no_object_result",<Result>)SetSystem("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_filterBinomialFilterbinomial_filterBinomialFilterBinomialFilter, gauss_filtergauss_filterGaussFiltergauss_filterGaussFilterGaussFilter, sigma_imagesigma_imageSigmaImagesigma_imageSigmaImageSigmaImage, median_imagemedian_imageMedianImagemedian_imageMedianImageMedianImage, smooth_imagesmooth_imageSmoothImagesmooth_imageSmoothImageSmoothImage

Alternatives

sobel_ampsobel_ampSobelAmpsobel_ampSobelAmpSobelAmp, kirsch_ampkirsch_ampKirschAmpkirsch_ampKirschAmpKirschAmp, prewitt_ampprewitt_ampPrewittAmpprewitt_ampPrewittAmpPrewittAmp, robinson_amprobinson_ampRobinsonAmprobinson_ampRobinsonAmpRobinsonAmp, robertsrobertsRobertsrobertsRobertsRoberts

See also

bandpass_imagebandpass_imageBandpassImagebandpass_imageBandpassImageBandpassImage, laplace_of_gausslaplace_of_gaussLaplaceOfGausslaplace_of_gaussLaplaceOfGaussLaplaceOfGauss

Module

Foundation