MATLAB: Differences between two photos

Image Processing Toolboxmatlab images differences

Hey guys! I'm new on matlab and I'm trying to do one thing, but I do not get it. The problem is that, for example, imagine there is a table and we take a photo. After this we put some element above the table ,for example, an apple and we take another photo. So, the question is, How can I determine the ROI (Region Of Interest) from the difference between the two images?

I was reading about roifilt2, roicolor… but I do not know how to apply that to it.

Thank you, kss!! =)

Best Answer

Try simply subtracting the images.

diffImage = double(image1) - double(image2);
imshow(diffImage, []);

Casting to double is important otherwise you will never get negative numbers. Also, the [] in imshow() lets you see both positive and negative numbers. If you want a binary image and have a color image, then you can use the max function, something like

diffImage = max(abs(diffImage), [], 3)  % For a color image.

Nothing more to do for a gray scale image. Then

binaryImage = abs(diffImage) > 5; % Or whatever number works.

Related Solutions

MATLAB: Grayscale and binary at the same figure with high QUALITY!

Stitch them together, like this:

% First need to make the binary image in the range 0-255 instead of 0-1 so you can see it.

binaryImage = 255 * uint8(binaryImage);
stitchedImage = [grayImage, binaryImage];
imshow(stitchedImage, []);

Here's a full blown demo:

clc;    % Clear the command window.
close all;  % Close all figures (except those of imtool.)
imtool close all;  % Close all imtool figures if you have the Image Processing Toolbox.
clear;  % Erase all existing variables. Or clearvars if you want.
workspace;  % Make sure the workspace panel is showing.
format long g;
format compact;
fontSize = 20;
% Read in a standard MATLAB gray scale demo image.
folder = fullfile(matlabroot, '\toolbox\images\imdemos');
baseFileName = 'cameraman.tif';
% Get the full filename, with path prepended.
fullFileName = fullfile(folder, baseFileName);
% Check if file exists.
if ~exist(fullFileName, 'file')
  % File doesn't exist -- didn't find it there.  Check the search path for it.
  fullFileName = baseFileName; % No path this time.
  if ~exist(fullFileName, 'file')
    % Still didn't find it.  Alert user.
    errorMessage = sprintf('Error: %s does not exist in the search path folders.', fullFileName);
    uiwait(warndlg(errorMessage));
    return;
  end
end
grayImage = imread(fullFileName);
% Get the dimensions of the image.  
% numberOfColorBands should be = 1.
[rows, columns, numberOfColorBands] = size(grayImage);
if numberOfColorBands > 1
  % It's not really gray scale like we expected - it's color.
  % Convert it to gray scale by taking only the green channel.
  grayImage = grayImage(:, :, 2); % Take green channel.
end
% Display the original gray scale image.
subplot(1,2,1);
imshow(grayImage, []);
title('Original Grayscale Image', 'FontSize', fontSize);
% Enlarge figure to full screen.

set(gcf, 'Units', 'Normalized', 'OuterPosition', [0 0 1 1]);
% Give a name to the title bar.

set(gcf, 'Name', 'Demo by ImageAnalyst', 'NumberTitle', 'Off') 
% Create a binary image by thresholding.
binaryImage = grayImage > 100;
subplot(1,2,2);
imshow(binaryImage, []);
title('Binary Image', 'FontSize', fontSize);
% Create a new figure window.
figure;
% Stitch them together.
% First need to make the binary image in the range 0-255 instead of 0-1 so you can see it.
binaryImage = 255 * uint8(binaryImage);
stitchedImage = [grayImage, binaryImage];
imshow(stitchedImage, []);
title('Stitched Image', 'FontSize', fontSize);
% Enlarge figure to full screen.
set(gcf, 'Units', 'Normalized', 'OuterPosition', [0 0 1 1]);
% Give a name to the title bar.
set(gcf, 'Name', 'Demo by ImageAnalyst', 'NumberTitle', 'Off')

MATLAB: How to validate contrast adjusting using imadjust comparing to other contrast adjusting techniques and original image

You can cast the images to double then subtract them to see the differences

diffImage = double(image1) - double(image2);
imshow(diffImage, []);
impixelinfo;

You can also view the values in the workspace/variable inspector - just double-click on the variable name in the workspace panel.

Best Answer

Related Solutions

MATLAB: Grayscale and binary at the same figure with high QUALITY!

MATLAB: How to validate contrast adjusting using imadjust comparing to other contrast adjusting techniques and original image

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