Thread Subject:

Use of histeq() as a parameter in nlfilter / colfilt

While performing neighborhood operations using nlfilter or colfilt, I noticed that the use of histeq as a parameter did not work and resulted in the error:

 "??? Assignment has more non-singleton rhs dimensions than non-singleton
subscripts

Error in ==> nlfilter at 75
        b(i,j) = feval(fun,x,params{:});
".

This code works fine:

                 output=colfilt(input,[m n],'sliding',@mean);

while this doesn't (replaced @mean with @histeq):

                 output=colfilt(input,[m n],'sliding',@histeq);

Can anyone explain why? Is there another better way to perform local histogram equalization? Thank you for your time.