How dispaly .mat as an image, then save it, then crop the saved image from the center ?

-looking to dispaly multi (.mat) files as images

-save or crop the center then save the cropped images it

[Rik]

Mat files store variables. Those may or may not be images.

What did you try? What is your specific question? Do you have trouble loading the data? Is your issue displaying the image? Don't you see how you should export a figure as an image?

And would you want that? Wouldn't it make more sense if you simply use imwrite?

[Mohamed Elbeialy]

.mat is a structure files and not images.

looking to display each mat. file as image

then save each outcome image with its orginal .mat file name

then crop the center of each outcome image and save it again under the same name

[Rik]

Your comment does not make it more clear for me what you want. What does each mat file actually contain? And it sounds like you want to display a struct as an image, but I have no clue how you would want to do that.

[Mohamed Elbeialy]

Each mat. file contains Array not image. This Array is the one that I look to display. Then , crop from center then save

[Rik]

If the array is not an image, how are you proposing to display it?

Don't forget that an image is actually a 2D array with some values (3D in the case of color images).

[Mohamed Elbeialy]

This is what I am looking to get help with

[Image Analyst]

If the help in my Answer below did not work for you, then attach one of the mat files with the paperclip icon and tell us what part of the center you want to save and what you'd like the output filename to be.

Answer 1

[Image Analyst]

Use the FAQ to read in a sequence of lots of .mat files.

https://matlab.fandom.com/wiki/FAQ#How_can_I_process_a_sequence_of_files.3F

In the loop, get your image from the mat file then crop it. Here's a start.

% Specify the folder where the files live.
myFolder = pwd; % or wherever, like 'C:\Users\yourUserName\Documents\My Pictures';
% Check to make sure that folder actually exists.  Warn user if it doesn't.
if ~isfolder(myFolder)
    errorMessage = sprintf('Error: The following folder does not exist:\n%s\nPlease specify a new folder.', myFolder);
    uiwait(warndlg(errorMessage));
    myFolder = uigetdir(); % Ask for a new one.
    if myFolder == 0
         % User clicked Cancel
         return;
    end
end
% Get a list of all files in the folder with the desired file name pattern.
filePattern = fullfile(myFolder, '*.mat'); % Change to whatever pattern you need.
theFiles = dir(filePattern);
for k = 1 : length(theFiles)
    baseFileName = theFiles(k).name;
    fullFileName = fullfile(theFiles(k).folder, baseFileName);
    fprintf(1, 'Now reading %s\n', fullFileName);
    % Now do whatever you want with this file name,
    % such as reading it in as an image array with imread()
	s = load(fullFileName);
	% See if this structure has a field called myImage or whatever it's called in your programs.
	if isfield(s, 'myImage')
		imageArray = imread(fullFileName);
                imageArray = imageArray(row1:row2, col1:col2, :);
		imshow(imageArray);  % Display image.
	        drawnow; % Force display to update immediately.
		fprintf('Displaying myImage from %s\n', baseFileName);
	else
		fprintf('   myImage not found in %s\n', baseFileName);
	end
end

Of course you need to assign row1, row2, col1, and col2 according to how you'd like to do the cropping.

[Mohamed Elbeialy]

I have attached .mat file. Please give me a help

[Image Analyst]

Not sure why my code and suggestions did not work for you. They worked fine for me.

% Specify the folder where the files live.
myFolder = pwd; % or wherever, like 'C:\Users\yourUserName\Documents\My Pictures';
% Check to make sure that folder actually exists.  Warn user if it doesn't.
if ~isfolder(myFolder)
    errorMessage = sprintf('Error: The following folder does not exist:\n%s\nPlease specify a new folder.', myFolder);
    uiwait(warndlg(errorMessage));
    myFolder = uigetdir(); % Ask for a new one.
    if myFolder == 0
         % User clicked Cancel
         return;
    end
end
% Get a list of all files in the folder with the desired file name pattern.
filePattern = fullfile(myFolder, '*.mat'); % Change to whatever pattern you need.
theFiles = dir(filePattern);
for k = 1 : length(theFiles)
    baseFileName = theFiles(k).name;
    fullFileName = fullfile(theFiles(k).folder, baseFileName);
    fprintf(1, 'Now reading %s\n', fullFileName);
    % Now do whatever you want with this file name,
    % such as reading it in as an image array with imread()
	s = load(fullFileName);
	% See if this structure has a field called myImage or whatever it's called in your programs.
	if isfield(s, 'HeatMapSum')
		fprintf('Displaying myImage from %s\n', baseFileName);
		imageArray = s.HeatMapSum;
		subplot(1, 2, 1);
		imshow(imageArray, []);  % Display image.
		title(baseFileName, 'Interpreter', 'none');

		%---------------------------------------------------------------------------------------------
		% Crop the image.
		row1 = round(size(imageArray, 1)/2) - 10;
		row2 = row1 + 19;
		col1 = round(size(imageArray, 2)/2) - 10;
		col2 = col1 + 19;
		croppedImage = imageArray(row1 : row2, col1 : col2, :);
		subplot(1, 2, 2);
		imshow(croppedImage, []);  % Display image.
		title('Cropped', 'Interpreter', 'none');
	        drawnow; % Force display to update immediately.
		
		%---------------------------------------------------------------------------------------------
		% Save the image.  Make the filename be the same name but with a PNG extension instead of MAT.
		baseFileName = strrep(lower(baseFileName), '.mat', '.png');
		outputFileName = fullfile(myFolder, baseFileName);
		% Rescale it to be 0-255
		croppedImage = uint8(255 * mat2gray(croppedImage));
		imwrite(croppedImage, outputFileName);
	else
		fprintf('   myImage not found in %s\n', baseFileName);
	end
end

I think you're just going to have to upload your code so we can figure out where you went wrong. Because it was pretty simple and straightforward so it shouldn't have been a problem. You probably just made a simple typo or other mistake.

[Mohamed Elbeialy]

Thank you a lot. This gave me some clues. However, the copped images have a white frame. How can I remove the white frame and keep the cropped images only

[Image Analyst]

My images did not have a white frame. Are you sure you used imwrite() and not saveas(), print(), or exportgraphics()?

[Mohamed Elbeialy]

Got it. Thanks