info_edgesT_info_edgesInfoEdgesInfoEdges (Operator)

Name

info_edgesT_info_edgesInfoEdgesInfoEdges — Estimate the width of a filter in edges_imageedges_imageEdgesImageEdgesImageEdgesImage.

Signature

info_edges( : : Filter, Mode, Alpha : Size, Coeffs)

info_edgesinfo_edgesInfoEdgesInfoEdgesInfoEdges returns an estimate of the width of any of the filters used in edges_imageedges_imageEdgesImageEdgesImageEdgesImage. 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. AlphaAlphaAlphaAlphaalpha is the filter parameter (see edges_imageedges_imageEdgesImageEdgesImageEdgesImage). Seven edge operators are supported (parameter FilterFilterFilterFilterfilter):

'deriche1', 'lanser1', 'deriche2', 'lanser2', 'shen', 'mshen' and 'canny'.

The parameter ModeModeModeModemode ('edge'/'smooth') is used to determine whether the corresponding edge or smoothing operator is to be sampled. The Canny operator (which uses the Gaussian for smoothing) is implemented using conventional filter masks, while all other filters are implemented recursively. Therefore, for the Canny filter the coefficients of the one-dimensional impulse responses are returned in CoeffsCoeffsCoeffsCoeffscoeffs in addition to the filter width.

Attention

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.

Execution Information

Multithreading type: reentrant (runs in parallel with non-exclusive operators).
Multithreading scope: global (may be called from any thread).
Processed without parallelization.

Parameters

FilterFilterFilterFilterfilter (input_control) string → (string)

Name of the edge operator.

Default value: 'lanser2' "lanser2" "lanser2" "lanser2" "lanser2"

List of values: 'canny'"canny""canny""canny""canny", 'deriche1'"deriche1""deriche1""deriche1""deriche1", 'deriche2'"deriche2""deriche2""deriche2""deriche2", 'lanser1'"lanser1""lanser1""lanser1""lanser1", 'lanser2'"lanser2""lanser2""lanser2""lanser2", 'mshen'"mshen""mshen""mshen""mshen", 'shen'"shen""shen""shen""shen"

ModeModeModeModemode (input_control) string → (string)

1D edge filter ('edge') or 1D smoothing filter ('smooth').

Default value: 'edge' "edge" "edge" "edge" "edge"

List of values: 'edge'"edge""edge""edge""edge", 'smooth'"smooth""smooth""smooth""smooth"

AlphaAlphaAlphaAlphaalpha (input_control) real → (real)

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 Alpha Alpha Alpha alpha ≤ 50.0

Minimum increment: 0.01

Recommended increment: 0.1

Restriction: Alpha > 0.0

SizeSizeSizeSizesize (output_control) integer → (integer)

Filter width in pixels.

CoeffsCoeffsCoeffsCoeffscoeffs (output_control) integer-array → (integer)

For Canny filters: Coefficients of the “positive” half of the 1D impulse response.

Example (HDevelop)

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)

Example (C)

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);

Example (HDevelop)

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)

Example (HDevelop)

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)

Example (HDevelop)

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)