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 2 (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.

kirsch_dir is reentrant and automatically parallelized (on tuple level, channel level, domain level).

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