info_edges — Return the filter coefficients of a filter in edges_image.
info_edges returns the coefficients Coeffs and an estimate of the width Size of any of the filters used in edges_image. To do so, the corresponding continuous impulse responses of the filters are sampled until the first filter coefficient is smaller than five percent of the largest coefficient. Alpha is the filter parameter (see edges_image). Seven edge operators are supported (parameter Filter):
'deriche1', 'lanser1', 'deriche2', 'lanser2', 'shen', 'mshen' and 'canny'.
The parameter Mode ('edge'/'smooth') is used to determine whether the corresponding edge or smoothing operator is to be sampled.
The Canny operator (which uses Gaussian smoothing) is implemented using conventional filter masks. Therefore, for the Canny filter, the coefficients Coeffs of the one-dimensional impulse responses are returned as . All other filters are implemented recursively; here, the Coeffs are coefficients of a corresponding non-recursive filter.
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.
Name of the edge operator.
Default value: 'lanser2'
List of values: 'canny', 'deriche1', 'deriche2', 'lanser1', 'lanser2', 'mshen', 'shen'
1D edge filter ('edge') or 1D smoothing filter ('smooth').
Default value: 'edge'
List of values: 'edge', 'smooth'
Filter parameter: small values result in strong smoothing, and thus less detail (opposite for 'canny').
Default value: 0.5
Typical range of values: 0.2 ≤ Alpha ≤ 50.0
Minimum increment: 0.01
Recommended increment: 0.1
Restriction: Alpha > 0.0
Filter width in pixels.
For Canny filters: Coefficients of the “positive” half of the 1D impulse response. All others: Coefficients of a corresponding non-recursive filter.
read_image(Image,'fabrik') info_edges('lanser2','edge',0.5,Size,Coeffs) edges_image(Image,Amp,Dir,'lanser2',0.5,'none',-1,-1) hysteresis_threshold(Amp,Margin,20,30,30)
info_edges returns 2 (H_MSG_TRUE) if all parameters are correct. If the input is empty the behavior can be set via set_system('no_object_result',<Result>). If necessary, an exception is raised.
edges_image, threshold, skeleton