Unable to determine the file format error. How can i solve this in matlab?

I've made code for face recognition, but i get this error. Anyone help me? Here is my code:

      function histSLGS = FP_FaceRecognition_Neat

      directory = uigetdir;
      imageVolum = [];

      for i = 1:23
      %imageVolume = [];
      %directoryFinal = cell(23,1);
      garing = '\';
      extension = '.txt';
      strI = num2str(i);
      directoryFinal = strcat(directory,garing,strI);
      fileList = dir(directoryFinal);
      %fl = fileList
      %DF = directoryFinal
      %a = numel(fileList)
      for idx = 3:numel(fileList)
      tempImage = imread(fullfile(directoryFinal, fileList(idx).name));
      imageVolum(:,:,:,idx) = tempImage;
      end
      %sI = size(imageVolum)
      for j = 3:33
      strJ = num2str(j);
      garis = '_';
      fileNameFinal = cell(30,1);
      fileNameFinal = strcat(directoryFinal,garing,strI,garis,strJ,extension); 
      imgManipulation3 = SLGS(imageVolum(:,:,:,j));
      histSLGS = hist(imgManipulation3);
      [rowhist, columnhist] = size(histSLGS);
      %r = rowhist
      %c = columnhist
      %fn = fileNameFinal
      fid = fopen(fileNameFinal, 'w');
      for l = 1:rowhist
      for k = 1:columnhist
      fprintf(fid, '%.3f, ', histSLGS(l,k));
      end
      fprintf(fid, '\n');
      end
      fclose(fid);
      histSLGS;
      end
      end

I got this error message:

Unable to determine the file format.

Error in ==> FP_FaceRecognition_Neat at 18 tempImage = imread(fullfile(directoryFinal, fileList(idx).name));

Your help is very hopeful.. :) Thanks..

Answer 1

[Guillaume]

You're just doing a plain dir, listing all files and directories in directoryFinal and passing each of these to imread. Of course, it's going to choke if one of those is a directory or a non-image file.

Either wrap the content of the for loop into a try ... catch statement, or restrict your dir to image files.

----

Side note: I would also reorganise the code to move variable declaration to just before where it's needed (e.g. extension), use fullfile to build path rather than hardcode the path separator, use sprintf to build filenames, and get rid of the preinitialisations to cell arrays that get immediately overwritten by a string (e.g. filenamefinal).

[Petrus Gumarang]

sorry, i don't understand your answer enough.. Can you explain me details? Sorry.

[Guillaume]

You're getting the content of directoryFinal with this line:

fileList = dir(directoryFinal);

where directoryFinal is

'somepath\1' %or 'somepath\2' or 'somepath\3', etc.

You then pass this content to imread. If, for example, in that directory you have a text file starting with one

1doesnotmatter.txt

or a directory starting with one

1doesnotmatter\

This is going to be passed to imread which won't know what do with it and tell you it can't determine the image format.

To fix it, either only list the file of the image format you're using, e.g. for png:

fileList = dir(fullfile(directory, sprintf('%d*.png', i)))

Or wrap the content of the for loop processing each file in a try catch statement:

for idx = 3:numel(fileList)
  try
     tempImage = imread(fullfile(directoryFinal, fileList(idx).name));
     imageVolum(:,:,:,idx) = tempImage;
  catch exception
     if strcmp(exception.identifier, 'MATLAB:imagesci:imread:fileFormat')
        warning('skipped reading %s. Not an image', fileList(idx).name);
     else %some other unknown error. stop execution
        rethrow(exception);
     end
  end
end