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

Question

Mohamed Elbeialy 2020-11-23

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https://ww2.mathworks.cn/matlabcentral/answers/659418-how-dispaly-mat-as-an-image-then-save-it-then-crop-the-saved-image-from-the-center

评论： Mohamed Elbeialy 2020-11-25

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

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

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Mohamed Elbeialy 2020-11-24

This is what I am looking to get help with

Image Analyst 2020-11-24

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.

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Answer 1

Image Analyst 2020-11-24

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https://ww2.mathworks.cn/matlabcentral/answers/659418-how-dispaly-mat-as-an-image-then-save-it-then-crop-the-saved-image-from-the-center#answer_554703

在 MATLAB Online 中打开

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.

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Image Analyst 2020-11-24

在 MATLAB Online 中打开

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.

Image Analyst 2020-11-25

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

Mohamed Elbeialy 2020-11-25

Got it. Thanks

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

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

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