Median Filter code problem:

Hello Dear Experts,

I am trying to build the median filter with given window size. Here is what I did so far, please correct me because for some reason I don't get the right results:

function [ newImg ] = myMedian( img, rows, cols )

ModifyImg = padarray(img,[1 1]);

for i = 1:(size(ModifyImg,1) - 2)
    for j = 1:(size(ModifyImg,2) - 2)
        window = zeros(rows,cols);
        inc = 1;
        for x = 1:rows
            for y = 1:cols
                window(inc) = ModifyImg(i + x - 1, j + y - 1);
                inc = inc + 1;
            end
        end

          Sorted_Window = sort(window);
          newImg(i,j) = Sorted_Window(ceil(0.5*rows*cols));
      end
  end
  end

Answer 1

[Image Analyst]

Try something like this (untested):

function [ newImg ] = myMedian( img, rows, cols )

ModifyImg = padarray(img,[1 1]);

for i = 1:(size(ModifyImg,1) - 2)
  for j = 1:(size(ModifyImg,2) - 2)
    window = ModifyImg(i:i+rows-1, j:j+cols-1);
    Sorted_Window = sort(window(:));
    newImg(i,j) = Sorted_Window(ceil(0.5*rows*cols));
  end
end

By the way, if you want to see how it's done with blockproc, in jumps of 8 pixels, see this demo code:

% Demo code to divide the image up into 16 pixel by 16 pixel blocks
% and replace each pixel in the block by the median, mean, or standard
% deviation of all the gray levels of the pixels in the block.
clc;
clearvars;
close all;
workspace;
fontSize = 20;

% Change the current folder to the folder of this m-file.
if(~isdeployed)
  cd(fileparts(which(mfilename)));
end

% Read in a standard MATLAB gray scale demo image.
folder = fullfile(matlabroot, '\toolbox\images\imdemos');

if ~exist(folder, 'dir')
  % If that folder does not exist, don't use a folder
  % and hope it can find the image on the search path.
  folder = [];
end
baseFileName = 'cameraman.tif';
fullFileName = fullfile(folder, baseFileName);
grayImage = imread(fullFileName);
% Get the dimensions of the image.  numberOfColorBands should be = 1.
[rows columns numberOfColorBands] = size(grayImage)
% Display the original gray scale image.
subplot(2, 2, 1);
imshow(grayImage, []);
title('Original Grayscale Image', 'FontSize', fontSize);

% Enlarge figure to full screen.
set(gcf, 'Position', get(0,'Screensize')); 
set(gcf,'name','Demo by ImageAnalyst','numbertitle','off') 

% Define the function that we will apply to each block.
% First in this demo we will take the median gray value in the block.
medianFilterFunction = @(x)median(x(:))*ones(size(x),class(x));

% Block process the image to replace every pixel in the 
% 8 pixel by 8 pixel block by the median of the pixels in the block.
blockSize = [8 8];
blockyImage8 = blkproc(grayImage, blockSize, medianFilterFunction);

% Display the block median image.
subplot(2, 2, 2);
imshow(blockyImage8, []);
title('Block Median Image', 'FontSize', fontSize);

[Steve]

Thanks a lot Image analyst!!!

Answer 2

[Hammad Moussa]

you can help me for fonction filtre media and filtre gaussian script. m

[Image Analyst]

Is this an answer to @Steve, who posted this 9 years ago? I doubt he will help you, and doubt he will even see your answer/question. You'd be best off posting your own question after reading this:

TUTORIAL: How to ask a question (on Answers) and get a fast answer

[Steve Solun]

@Image Analyst Actually it was a great nostalgy to see this question, wow 9 years ago :)

So I do see and get updates :)

@Hammad MoussaI think you can easily find a tutorial for what you're asking by searching G.