what is the error here?

i want to make a mode filter for the red channel of an image by using a simple GUI i wrote my code and it doesn't work

function mod_filter_Callback(hObject, eventdata, handles)
global image;
red=image(:,:,1);
modeImage=colfilt(red, [5 5], 'sliding', @mode);
axes(handles.axes16);
imshow(modeImage,[]);

[Adam]

It may not be causing a problem here, but don't use builtin function names ( 'image' ) as variable names.

Given it is a global variable I have no idea what kind of mess that could cause, maybe no more than a normal variable, but I would strongly advise against using global variables in any case.

You failed to say in what way your code "doesn't work" though. It is a lot easier for us to help if you give us full information!

Answer 1

[Image Analyst]

You can use blockproc():

% Demo code to divide the image up into 5 pixel by 5 pixel blocks
% and replace each pixel in the block by the mode
% of all the gray levels of the pixels in the block.
%
clc;
clearvars;
close all;
workspace;
fontSize = 16;

% Read in a standard MATLAB gray scale demo image.
folder = fileparts(which('cameraman.tif'));
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(1, 2, 1);
imshow(grayImage, []);
caption = sprintf('Original Grayscale Image\n%d rows by %d columns',...
  rows, columns);
title(caption, 'FontSize', fontSize);

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

% Block process the image to replace every pixel in the 
% 5 pixel by 5 pixel block by the mode
% of the pixels in the block.
% Image will be smaller since we are not using ones() and so for each block
% there will be just one output pixel, not a block of 5 by 5 output pixels.
blockSize = [5 5];
modeFilterFunction = @(theBlockStructure) mode(double(theBlockStructure.data(:)));
blockyImageMode = blockproc(grayImage, blockSize, modeFilterFunction);
[rows, columns] = size(blockyImageMode);

% Display the block mode filtered image.
subplot(1, 2, 2);
imshow(blockyImageMode, []);
title('Mode Filtered Image', 'FontSize', fontSize);
caption = sprintf('Block Mode Filtered Image\n32 blocks. Input block size = %d, output block size = 1\n%d rows by %d columns',...
  blockSize(1), rows, columns);
title(caption, 'FontSize', fontSize);

[esraa]

i tried this but still not working

global img;
red=img(:,:,1);
blockSize = [5 5];
StDevFilterFunction = @(theBlockStructure) mode(double(theBlockStructure.data(:)));
blockyImageMode = blockproc(red, blockSize, StDevFilterFunction);
imshow(blockyImageMode, []);
axes(handles.axes16);

[Image Analyst]

What does it do? Can you attach your image?