How to convert a folder with multiple type of images such as PNG, GiF, JEPG,...etc into JPG and store the converted images in a folder in desktop ?

How to convert a folder with multiple type of images such as PNG, GiF, JPEG,...etc into JPG and store the converted images in a folder in desktop ?

[Walter Roberson]

What kind of file do you have that has multiple types of images stored inside it?

Answer 1

[Akira Agata]

How about the following script?

fileList = {'ngc6543a.jpg','corn.tif'};

for kk = 1:numel(fileList)
  I = imread(fileList{kk});
  [~,fileName,ext] = fileparts(fileList{kk});
  imwrite(I,[fileName,'.png']);
end

[Image Analyst]

What about multi-image files like GIF image files (which have a series of still images in them), or multi-page TIFF files?

[Walter Roberson]

animated GIF and multi-page TIFF do not have multiple types of images stored in the same file like the person was asking for.

The only kind of file I can think of that could have multiple types of images stored is a database or a .mat file or a binary file in which the entire image files had been read in as binary blobs and stored as streams of bytes.

[Image Analyst]

I'm not sure he actually meant what he said. Maybe he meant "How to convert a folder with ..." or "How to convert a file with multiple images in it...". Hopefully he will clarify.

[Akira Agata]

Hi Walter-san and Image Analyst-san,

Thank you for the clarification. When posting my answer, I prematurely jumped to the wrong(?) understanding that the question means "How to convert a folder with ..." But, as you clarified, the original question reads "How to convert a file with ..."

Honelsty, I'm not sure what this means, too.

[D. Frank]

Hi Mr.Walter, Mr.Image Analyst and Akira-san I'm really sorry for my unclear question, the problem that i'm facing with is that i have a folder with a lot of images with different types such as GIF, PNG, JEPG,...etc, and i want to convert all of them into .jpg and store them in a new folder in desktop, Thank you.

[Akira Agata]

Hi Duy-san,

Thank you for the clarification. OK, I believe the following code can do that !

imgFolder = yourImgFolder;
fileList = struct2table(dir([imgFolder,'/*.*']));

% Extract .gif, .png, .jpeg and .bmp files
c = regexp(fileList.name,'[\w]*.(gif|png|jpeg|bmp)');
idx = cellfun(@isempty,c);
fileList(idx,:) = [];

% Set the output folder
outputFolder = yourOutputFolder;

% Convert to .jpg and save to the output folder
for kk = 1:height(fileList)
  I = imread(...
    fullfile(fileList.folder{kk},fileList.name{kk}));
  [~,fileName,ext] = fileparts(fileList.name{kk});
  imwrite(I,fullfile(outputFolder, [fileName, '.jpg']));
end

[Walter Roberson]

Note that JPEG is a lossy format, and should not be used for image analysis or scientific research.

[D. Frank]

I don't know why but the matlab show that" Error using table/subsrefDot" and "Unrecognized variable name 'folder' ". Thank you

[Walter Roberson]

imgFolder = yourImgFolder;
dinfo = dir(imgFolder);
dinfo([dinfo.isdir]) = [];

fileList = fullfile(imgFolder, {dinfo.name});

% Extract .gif, .png, .jpeg and .bmp files
c = regexp(fileList, '\.(gif|png|jpg|jpeg|bmp)$', 'lineanchors');
idx = cellfun(@isempty,c);
fileList(idx) = [];

% Set the output folder
outputFolder = yourOutputFolder;

% Convert to .jpg and save to the output folder
for kk = 1: length(fileList)
  thisfile = fileList{kk};
  I = imread( thisfile );
  [~, fileName, ext] = fileparts(thisfile);
  imwrite(I, fullfile(outputFolder, [fileName, '.jpg']));
end

[D. Frank]

Thank you Mr.Walter, it works smoothly.

[Intan Antasari]

Hi, Mr. Walter.

How to convert into .mat and save to the output folder?

I tried your code, and I got an error with imwrite command.

Thank you for your help.

[Walter Roberson]

What error did you get with imwrite() ?

[Intan Antasari]

I got an error because I use imwrite to save .mat format.

I realize that imwrite is use to save image format. I already solve that problem.

I use save (filename, 'A')

Thank you for your help.

Answer 2

[Jos (10584)]

Why not use a dedicated tool to convert images, like good-old IrfanView (does it still exist?) or gimp?

Answer 3

[cui,xingxing]

you can write like this,but can get all images from website(note: modify your urls):

clc
clear
% s=urlread('https://image.baidu.com/search/index?tn=baiduimage&ipn=r&ct=201326592&cl=2&lm=-1&st=-1&sf=1&fmq=&pv=&ic=0&nc=1&z=&se=1&showtab=0&fb=0&width=&height=&face=0&istype=2&ie=utf-8&fm=result&pos=history&word=%E6%B8%85%E6%9C%9D%E7%A1%AC%E5%B8%81');
s = webread('https://mp.weixin.qq.com/s/WlGxKjirx1iKqwmfMzVI0g');
pat='https://[^,"]*.=(jpg|png|gif|jpeg)';
% pat='http://[^,]*.jpg';
expr= regexp(s, pat, 'match');

%%
fid=fopen('images.txt','w');
fprintf(fid,'%s\n',expr{:});
fclose(fid);

for i=1:length(expr)
    img_url =expr{i};
    try
%         s=websave(a,sprintf('%d.jpg',i), 'UserAgent','MATLAB R2015b','Timeout',100,'Get',{'term','urlread'});
          s = websave(['./',sprintf('%d.jpg',i)],img_url);
    catch ME
        continue
    end
end

%% show urls
imgs = string(expr);
for i = 1:length(imgs)
    fprintf('%s\n',imgs(i));
end

% reference: https://stackoverflow.com/questions/169625/regex-to-check-if-valid-url-that-ends-in-jpg-png-or-gif