Hello guys, I have a question concerning my Matlab script. I try to read/load several pictures but I always get the same error. Could anyone have a quick look at my script? The files I try to load defintely exist and they all have the .jpg format.

affectivepictures = dir('C:\Users\Kilian\Desktop\Arbeit Köln\Matlab\Bilddateien\affektive_Bilder_neu/*.jpg');

numFiles = length(affectivepictures); 

for i_pics = 1:numFiles

bild = imread(affectivepictures(i_pics).name);

image{i_pics} = double(bild)/255;
% convert image matrices to textures

theImage{i_pics} = Screen('MakeTexture', window, image{i_pics});
end

[tom]

the error is: Error using imread>get_full_filename (line 516) File "1.jpg" does not exist.

Error in imread (line 340) fullname = get_full_filename(filename);

Could anyone help me out with this? Kind of desperate already

Answer 1

[Walter Roberson]

projectdir = 'C:\Users\Kilian\Desktop\Arbeit Köln\Matlab\Bilddateien\affektive_Bilder_neu';
affectivepictures = dir( fullfile(projectdir, '*.jpg') );
numFiles = length(affectivepictures); 
filenames = fullfile( projectdir, {affectivepictures.name});

for i_pics = 1:numFiles
  thisfile = filenames{i_pics};
  bild = imread(thisfile);
  images{i_pics} = im2double(bild);
  % convert image matrices to textures
  theImage{i_pics} = Screen('MakeTexture', window, images{i_pics});
end

[tom]

Thanks again. Maybe I´am way to stupid. I tried this

projectdir = 'C:\Users\Kilian\Desktop\Arbeit Köln\Matlab\Bilddateien\affektive_Bilder_neu';

affectivepictures = dir( fullfile(projectdir, '*.jpg') );

numFiles = length(affectivepictures); 
filenames = fullfile( projectdir, {affectivepictures.name});

for i_pics = 1:numFiles
  thisfile = filenames{i_pics};

    bild = imread(thisfile);

    images{i_pics} = im2double(bild);

    % convert image matrices to textures
    theImage{i_pics} = Screen('MakeTexture', window, images{i_pics});
  end
  Identification=1:numFiles;
  Identification=Shuffle(Identification);

The script starts now but I receive an error at another line. I´m just confused because it already worked out.

Undefined function or variable 'theImage'.  
Screen('DrawTexture', window, theImage{Identification(trial)}, [], instrImagePosition);

Best regards and thanks in advance

[tom]

maybe this is helpful. When I just submit this:

projectdir = 'C:\Users\Kilian\Desktop\Arbeit Köln\Matlab\Bilddateien\affektive_Bilder_neu';
affectivepictures = dir( fullfile(projectdir, '*.jpg') );
numFiles = length(affectivepictures); 

filenames = fullfile( projectdir, {affectivepictures.name});

it creates a structure 0x1 (so nothing in it?)

[Walter Roberson]

What shows up for

 ls(projectdir)

?

One thing I worry about is the ö in your string. In English versions of MATLAB, .m files are not stored as UTF-8, so although the ö would show up on your screen, what would be saved in the file might be something different. It is probably okay because ö is char(246) rather than being something about 255 that would require two bytes to represent, but it is something I would double check.

[Image Analyst]

The line of code you posted is

theImage{i_pics} = Screen('MakeTexture', window, images{i_pics});

yet the error is regarding this line of code:

Screen('DrawTexture', window, theImage{Identification(trial)}, [], instrImagePosition);

which is not in the code you posted. Note that the third argument of Screen() is "images" in the first code and "theImage" in the second code. So which is it? If you're using the second line of code, then theImage has never been defined yet so that's why you're getting the error message.

I think you need to take more care about your variable names and which are used where, and also in showing us the proper code and matching error message.

Answer 2

[KL]

Probably you're not working on the same directory. Try using fullfile,

 bild = imread(fullfile(affectivepictures(i_pics).path,affectivepictures(i_pics).name));

[tom]

Hey KL, thanks for your answer. Now I get this error "Reference to non-existent field 'path'."

sorry, I´am completely new to the field.

The strange thing is, a few days ago it already worked out fine with the Code above. I don´t think I changed something about it.

Any other ideas? Best regards

[Walter Roberson]

The 'path' field for dir() was new as of a small number of releases ago.

Answer 3

[Image Analyst]

You forgot to use fullfile() to prepend the folder.

This is a very F.A.Q. So see the faq (the second chunk of code): http://matlab.wikia.com/wiki/FAQ#How_can_I_process_a_sequence_of_files.3F

Answer 4

[tom]

Thank you all!

It works now totally fine. First question --> first answer. Great community.

best regards Kilian