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.
Image (input_object) |
image(-array) -> object : byte |
Input image. |
ImageEdgeAmp (output_object) |
image(-array) -> object : byte |
Edge amplitude (gradient magnitude) image. |
read_image(:Image:'fabrik':) > prewitt_amp(Image:Prewitt::) > threshold__(Prewitt:Edges:128,255:).
prewitt_amp always returns TRUE. If the input is empty the behaviour can be set via set_system(::'no_object_result',<Result>:). If necessary, an exception is raised.
gauss__, sigma__, median, smooth__
threshold__, grey_skeleton__, nonmax_suppression_amp, close_edges1, close_edges2
sobel_amp, kirsch_amp, frei_amp, robinson_amp, roberts__