frei_ampfrei_ampFreiAmpFreiAmpfrei_amp (Operator)

Name

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

Signature

Description

frei_ampfrei_ampFreiAmpFreiAmpFreiAmpfrei_amp 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 The result image contains the maximum response of the masks A and B.

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')
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_ampFreiAmpFreiAmpFreiAmpfrei_amp 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>)SetSystem("no_object_result",<Result>)SetSystem("no_object_result",<Result>)set_system("no_object_result",<Result>). If necessary, an exception is raised.

Possible Predecessors

binomial_filterbinomial_filterBinomialFilterBinomialFilterBinomialFilterbinomial_filter, gauss_filtergauss_filterGaussFilterGaussFilterGaussFiltergauss_filter, sigma_imagesigma_imageSigmaImageSigmaImageSigmaImagesigma_image, median_imagemedian_imageMedianImageMedianImageMedianImagemedian_image, smooth_imagesmooth_imageSmoothImageSmoothImageSmoothImagesmooth_image

Alternatives

sobel_ampsobel_ampSobelAmpSobelAmpSobelAmpsobel_amp, kirsch_ampkirsch_ampKirschAmpKirschAmpKirschAmpkirsch_amp, prewitt_ampprewitt_ampPrewittAmpPrewittAmpPrewittAmpprewitt_amp, robinson_amprobinson_ampRobinsonAmpRobinsonAmpRobinsonAmprobinson_amp, robertsrobertsRobertsRobertsRobertsroberts

See also

bandpass_imagebandpass_imageBandpassImageBandpassImageBandpassImagebandpass_image, laplace_of_gausslaplace_of_gaussLaplaceOfGaussLaplaceOfGaussLaplaceOfGausslaplace_of_gauss

Module

Foundation