How to save images as jpgs from .mat files struct

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Mamoona Nisar 2019-2-19

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/445766-how-to-save-images-as-jpgs-from-mat-files-struct

移动：DGM 2024-1-9

采纳的回答： Akira Agata

1.mat

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Hi ,I have 3064 .mat files dataset of brain tumors ,Prepareing data with lables for CNN.Each .mat file has struct 1x1 . Struct has following has these information: cjdata.image and cjdata.label.

And image is stored as cjdata.image.

I want to load all the .mat files:

1.mat ,2.mat ,3.mat ........................3064.mat

Want to apply these three opertions on each .mat file iteratively using a loop

1- accessing image from struct

2.convert into gray scale

3.save grayscale image as as 1.jpg 2.jpg.....3065.jpg

% Reading folder that has 3064 .mat files
myFolder = 'C:\Users\join2\Desktop\FIGSHARE\figshare data progress\figshare jpg data\3064 images';
filePattern = fullfile(myFolder, '*.mat');
Pgraymap = dir(filePattern);
 for I = 1:length(Pgraymap)
   baseFileName = Pgraymap(I).name;
   str = fullfile(myFolder, baseFileName);
   fprintf(1, 'Now reading %s\n', str);
   img1 = imread(str); % new
%  load .mat
   d=load(filePattern);
% acessing  images from  .mat files. each .mat has image as strcture,that
% is "cjdata.image"
   d.cjdata.image;
% gray scale conversion
   d=im2uint8(d);
% save all d.cjdata.image as jpgs in myFolder .plz help i don't know how to save
end

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采纳的回答

Akira Agata 2019-2-19

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/445766-how-to-save-images-as-jpgs-from-mat-files-struct#answer_361701

在 MATLAB Online 中打开

To save matrix as an image, please use imwrite function.

In addition, if you save your data as an image file, I would recommend saving as .tiff or .png to keep data accuracy, because .jpg is a lossy compression method.

The following is a simple example.

inputFolder = 'C:\Users\join2\Desktop\FIGSHARE\figshare data progress\figshare jpg data\3064 images';
outputFolder = pwd; % Please change, if needed.
fileList = dir(fullfile(inputFolder,'*.mat'));
for kk = 1:numel(fileList)
  S = load(fullfile(fileList(kk).folder,fileList(kk).name));
  I = S.cjdata.image;
  I = mat2gray(I);
  fileName = replace(fileList(kk).name,'.mat','.tiff');
  imwrite(I,fullfile(outputFolder,fileName));
end