2D majority filer in MATLAB?

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Elena Ranguelova
Elena Ranguelova on 24 Feb 2017
Answered: rgr478 on 7 Jul 2021
Hello,
Is there a 2D majority filter in MATLAB?
With ordfilt2 minimum, maximum, median etc. filters can be implemented, but not majority. Is there another command with that functionality?
Here 'majority filter' means replacing each element of a matrix by the most frequently occurring element in a set of neighbors of that element.
Regards, Elena
  1 Comment
Elena Ranguelova
Elena Ranguelova on 24 Feb 2017
Maybe
blockproc
would help?
fun = @(block_struct) ...
mode(block_struct.data(:)) * ones(size(block_struct.data));
output_matrix = blockproc(input_matrix,[<size_x> <size_y>],fun);

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Answers (3)

Sailesh Sidhwani
Sailesh Sidhwani on 22 May 2019
Edited: Sailesh Sidhwani on 22 May 2019
There is no direct function for mode filtering, you can use the colfilt instead:
out = colfilt(img, [5 5], 'sliding', @mode) ;

Sailesh Sidhwani
Sailesh Sidhwani on 25 Nov 2020
A new 'modefilt' function for 2D and 3D data was added to Image Processing Toolbox in R2020a:
Both 'colfilt' and 'nlfilter' are generic sliding window functions and can be used to perform mode filtering but the expectation is that 'modefilt' to be faster than both of these functions and also work on 3D grayscale data.

rgr478
rgr478 on 7 Jul 2021
bwmorph(image,'majority')

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