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Importing multiple jpg files using imread. File format error.

Asked by Kelsey Frewin on 24 Jun 2016
Latest activity Commented on by Walter Roberson
on 24 Jun 2016
Recently created a subset of script to import a number of .jpg files by putting them in a loop. This script has been working perfectly for me, until today. I've not changed anything and have tried this both on my personal PC and University PCs, and still get the same error.
I got the information for the script from this link and followed it exactly. http://uk.mathworks.com/help/matlab/import_export/process-a-sequence-of-files.html
My script looks like this:
jpegFiles = dir('*.jpg');
numfiles = length(jpegFiles);
images = cell(1, numfiles);
for k = 1:numfiles
images{k} = imread(jpegFiles(k).name);
end
Previously, as I mentioned, there have been no problems. I now suddenly get this error, and have tried all I can think of!
Error using imread (line 362)
Unable to determine the file format.
Error in imagesin (line 6)
images{k} = imread(jpegFiles(k).name);
I am new to this and any suggestions would be appreciated!
Thanks in advance.

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2 Answers

Answer by Walter Roberson
on 24 Jun 2016
 Accepted Answer

One of your files has a .jpg suffix but is not a valid JPEG file. Try
jpegFiles = dir('*.jpg');
numfiles = length(jpegFiles);
images = cell(1, numfiles);
for k = 1:numfiles
thisfile = jpegFiles(k).name;
try
images{k} = imread(thisfile);
catch
warning('File #%d, name "%s" does not appear to be a valid image, skipping it. The file size for it is %d bytes', k, thisfile, jpegFiles(k).bytes );
images{k} = uint8([]);
end
end

  3 Comments

Thanks for that.
When run, comes back with the below for the vast majority of files:
Warning: File #579, name "._Wmale_55neutral.jpg" does not appear to be a valid image, skipping it. The file size for it
is 4096 bytes
How should I proceed from here? Just unsure why this issue now, when I've not had problems with the script or files previously.
Just re-examined the folder and found a number of corrupted files. Issue seems to be sorted now they have been removed. Thank you so much!
You see that ._ ? That file is a thumbnail. It is likely the thumbnail will get generated again.
After you do
jpegFiles = dir('*.jpg');
do
isdotfile = strncmp({jpegFiles.name}, '.', 1);
jpegFiles(isdotfile) = [];

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Answer by Muhammad Usman Saleem on 24 Jun 2016

jpegFiles = dir('*.jpeg');
numfiles = size(jpegFiles);
try to use this

  1 Comment

Have input this, and get this error returned:
Error using cell
Size inputs must be scalar.
Error in imagesin (line 3)
images = cell(1, numfiles);

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