Reading in a file name with a zero

I am trying to read in image files named in numerical order. Example: IMG_0567, IMG_0568, etc.

I am using the following script to do this:

    source = 'G:\RESEARCH\Acetone\30x3_acetone_10deg_2013-05-01\SLR\';
    first = 0567; % first frame in sequence
    last = 0617; % last frame in sequence
    image1=imread([source,'IMG_', num2str(first),'.JPG'],'JPG');

It appears that MATLAB does not recognize the zero in the number of the image and I receive the following error:

Error using imread (line 388)
File
"G:\RESEARCH\Acetone\30x3_acetone_10deg_2013-05-01\SLR\IMG_567.JPG"
does not exist.

My solution so far has been to go in and manually change the name of the file to remove the zero, but for a thousand files this would be obnoxiously tedious.

Suggestions?

Answer 1

[Cedric]

You probably want to do something like this:

 for imgId = first : last
     fileLocator = fullfile(source, sprintf('IMG_%04d.JPG', imgId)) ;
     img = imread(fileLocator, 'JPG') ;
     % .. processing ..
 end

where %04d in the format spec. converts imgId to string over 4 characters with 0 padding if necessary.

[Daniel]

I was just in the process of finding out what %04d meant when I saw your edit.

Thank you, I will follow up with an answer acceptance when I have my script working.

[Cedric]

You can also use EXIST with a 'file' 2nd argument to check whether the file exists or not before trying to IMREAD it, or put the call to IMREAD in a TRY statement and CATCH failures.

Examples:

 for imgId = first : last
     fileLocator = fullfile(source, sprintf('IMG_%04d.JPG', imgId)) ;
     if ~exist(fileLocator, 'file'),  continue ;  end
     img = imread(fileLocator, 'JPG') ;
     % .. processing ..
 end

or

 for imgId = first : last
     fileLocator = fullfile(source, sprintf('IMG_%04d.JPG', imgId)) ;
     try
        img = imread(fileLocator, 'JPG') ;
     catch
        warning('Image "%s" not found.', fileLocator) ;
        continue ;
     end
     % .. processing ..
 end