prewitt_amp — Detect edges (amplitude) using the Prewitt operator.
prewitt_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 1 1 0 0 0 -1 -1 -1 B = 1 0 -1 1 0 -1 1 0 -1The result image contains the maximum response of the masks A and B.
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.
Edge amplitude (gradient magnitude) image.
read_image(Image,'fabrik') prewitt_amp(Image,Prewitt) threshold(Prewitt,Edges,128,255)
prewitt_amp always returns 2 (H_MSG_TRUE). If the input is empty the behavior can be set via set_system('no_object_result',<Result>). If necessary, an exception is raised.
binomial_filter, gauss_filter, sigma_image, median_image, smooth_image
threshold, gray_skeleton, nonmax_suppression_amp, close_edges, close_edges_length
sobel_amp, kirsch_amp, frei_amp, robinson_amp, roberts