MATLAB: How to load and process multiple images

datafilefilenamefilesfolderforimageimage processingImage Processing Toolboximagesloadloop

Hi everyone,

I came across the matlab wiki and found this code for loading up multiple images to process them, which I have slightly edited.

However, I am getting the following error

Error using load

Unknown text on line number 1 of ASCII file paganin_000001.tif

"II*"

I am not sure how to edit this code to read these files, I have 100 of these images. Do I need to convert these images from tif to png or jpeg? As I cannot upload .tif files onto here either too.

Any help would be appreciated, thanks.

for k = 1:20
  matFilename = sprintf('paganin_00000%d.tif', k);
  matData = load(matFilename);
  jpgFilename = strcat('image', num2str(k), '.jpg');
  imageData = imread(jpgFilename);
  textFilename = ['file' num2str(k) '.txt'];
  fid = fopen(textFilename, 'rt');
  textData = fread(fid);
  fclose(fid);
end

Best Answer

Try this:

for k = 1:20
  fileName = sprintf('paganin_00000%d.tif', k);
  if isfile(fileName)
        % If the file exists, display it.
        imageData = imread(fileName);
        imshow(imageData);
        drawnow;
  else
      % Print alert for those files that don't exist.
      fprintf('File not found: "%s".\n', fileName)
  end
end

Related Solutions

MATLAB: How to make .bin file

"I tried below code but it seems the binary file is not good". How do you define "good"?

Following code shows the image is saved and loaded properly.

img = imread('pears.png');
fid = fopen('test.bin', 'w+');
fwrite(fid, img, 'uint8');
fclose(fid);
fid = fopen('test.bin', 'r');
img_loaded = uint8(fread(fid, inf, 'uint8'));
fclose(fid);
img_loaded = reshape(img_loaded, size(img));
imshow(img_loaded);

MATLAB: How to load multiple images and processing them

Evidently you didn't see the FAQ: http://matlab.wikia.com/wiki/FAQ#How_can_I_process_a_sequence_of_files.3F

% Read files file1.txt through file20.txt, mat1.mat through mat20.mat
% and image1.jpg through image20.jpg.  Files are in the current directory.
for k = 1:20
  matFilename = sprintf('mat%d.mat', k);
  matData = load(matFilename);
  jpgFilename = strcat('image', num2str(k), '.jpg');
  imageData = imread(jpgFilename);
  textFilename = ['file' num2str(k) '.txt'];
  fid = fopen(textFilename, 'rt');
  textData = fread(fid);
  fclose(fid);
end

A very slight adaptation gives you:

% Read 1.jpg through m.jpg.  
% Files are in the "yourFolder" directory.
for k = 1:m
  jpgFilename = sprintf('%d.jpg', k);
  fullFileName = fullfile(yourFolder, jpgFilename);
  if exist(fullFileName, 'file')
    imageData = imread(fullFileName );
  else
    warningMessage = sprintf('Warning: image file does not exist:\n%s', fullFileName);
    uiwait(warndlg(warningMessage));
  end
  imshow(imageData);
end

Note how I make it more robust by using exist() to check for the file's existence before attempting to show it, and how I make it more flexible by allowing you to specify that the files live in some particular folder "yourFolder" rather than living in the current folder only.

However if you want to do all the image files in the folder, then use the second chunk of code in the FAQ. That will also eliminate the need to use exist() because dir() will only give you files that are known to exist. However, if you want to be alerted if a file is missing, then you could still use the part of the first example to warn you of a missing file.

Best Answer

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MATLAB: How to load multiple images and processing them

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