[Octave-bug-tracker] [bug #45088] image package: rangefilt requires domain and image to have equa number of dimensions

[Hartmut]

Follow-up Comment #11, bug #45088 (project octave):

* What does "K = rangefilt(R)" give in Matlab (with the script from comment
#9)?
** This is ment to answer the question: Are the results of rangefilt.m (with
simple 2d input images) currently Matlab compatible at all?

* I have the suspicion that our current Octave implementation of rangefilt
just gives results that are by +1 too big for this input value.
** The Matlab doc says about rangefilt: "J = rangefilt(I) returns the array J,
where each output pixel contains the range value (maximum value − minimum
value) of the 3-by-3 neighborhood around the corresponding pixel in the input
image I."
** If the above test gives the expected result "K == J(:,:,1)" then our Octave
results are abviously too big by +1 in this case. The difference between the
max value and the min value in a 3x3 region of R is 2, and not 3. (See for
example the center pixel, min=2, max=4.)
** This would be a new bug. Presumably in __spatial_filtering__.cc
** A minimal test code for debugging this new bug is for example this:

X=[0 1 0;0 0 2;0 0 0]
Y=rangefilt(X)
Y(2,2)   % should be 2 (=2-0), not 3




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