amedfilt2_vard.m

This file contains the material presented as the first Embedded MATLAB webinar on the MathWorks web

function J = amedfilt2_vard(I)
% 2-D Adaptive Median Filter
% This filter ignores edge effects and boundary conditions, as such, the
% output is a cropped version of the original image, where the amount
% cropped is equal to the maximum window size vertically and horizontally.

% Define smax as a constant
smax = 9;

% Initialize Output Image (J)
J = I;

% Calculate valid region limits for filter
[nrows ncols] = size(I);
ll = ceil(smax/2);
ul = floor(smax/2);

% Loop over the entire image ignoring edge effects
for rows = ll:nrows-ul
    for cols = ll:ncols-ul

        % These lines can be taken outside the inner loop
        window_ind = -ul:ul;
        region = I(rows+window_ind,cols+window_ind);
        centerpixel = region(ll,ll);

        for s = 3:2:smax
            
            % calculate zmin, zmax, zmed
            rmin = min(region(:));
            rmax = max(region(:));
            rmed = median(region(:));

            % adapt region size
            if rmed > rmin && rmed < rmax
                if centerpixel <= rmin || centerpixel >= rmax
                    J(rows,cols) = rmed;
                end

                % stop adapting
                break;
            end
        end
    end
end