info_smooth — Information on smoothing filter smooth_image.
The operator info_smooth returns an estimation of the
width of the smoothing filters used in routine smooth_image.
For this purpose the underlying continuous impulse answers of
Filter are scanned until a filter coefficient is smaller
than five percent of the maximum coefficient (at the origin).
Alpha is the filter parameter (see smooth_image).
Currently four filters are supported (parameter Filter):
'deriche1', 'deriche2', 'shen' and 'gauss'.
The gauss filter was conventionally implemented with filter masks
(the other three are recursive filters). In the case of the gauss
filter the filter coefficients (of the one-dimensional impulse
answer ) are returned
in Coeffs in addition to the filter size.
For an explanation of the concept of smoothing filters see the introduction of chapter Filters / Smoothing.
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.
Filter (input_control) string → (string)
Name of required filter.
Default value: 'deriche2'
List of values: 'deriche1', 'deriche2', 'gauss', 'shen'
Alpha (input_control) real → (real)
Filter parameter: small values effect strong smoothing (reversed in case of 'gauss').
Default value: 0.5
Suggested values: 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 4.0, 5.0, 7.0, 10.0
Typical range of values: 0.01
≤
Alpha
≤
50.0
Minimum increment: 0.01
Recommended increment: 0.1
Restriction: Alpha > 0.0
Size (output_control) integer → (integer)
Width of filter is approx. size x size pixels.
Coeffs (output_control) integer-array → (integer)
In case of gauss filter: coefficients of the “positive” half of the 1D impulse answer.
info_smooth('deriche2',0.5,Size,Coeffs)
smooth_image(Input,Smooth,'deriche2',7)
If the parameter values are correct the operator
info_smooth returns the value TRUE. Otherwise an
exception is raised.
Foundation