Detect edges (amplitude and direction) using the Kirsch operator.

::kirsch_dir 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: -3 -3 5 -3 5 5 5 5 5 5 5 -3 -3 0 5 -3 0 5 -3 0 -3 5 0 -3 -3 -3 5 -3 -3 -3 -3 -3 -3 -3 -3 -3 5 -3 -3 -3 -3 -3 -3 -3 -3 -3 -3 -3 5 0 -3 5 0 -3 -3 0 -3 -3 0 5 5 -3 -3 5 5 -3 5 5 5 -3 5 5 The result image contains the maximum response of all masks. The edge directions are returned in ImageEdgeDir, and are stored as x / 2. They correspond to the direction of the mask yielding the maximum response.

read_image(&Image,"fabrik");
kirsch_dir(Image,&Kirsch_dirA,&Kirsch_dirD);
threshold(Kirsch_dirA,&Res,128,255);

::kirsch_dir always returns H_MSG_TRUE. If the input is empty the behaviour can be set via ::set_system('no_object_result',<Result>). If necessary, an exception handling is raised.

::gauss_image, ::sigma_image, ::median_image, ::smooth_image

::hysteresis_threshold, ::threshold, ::gray_skeleton, ::nonmax_suppression_dir, ::close_edges, ::close_edges_length

::edges_image, ::sobel_dir, ::robinson_dir, ::prewitt_dir, ::frei_dir

::bandpass_image, ::laplace_of_gauss

Image filters