[Octave-bug-tracker] [bug #30365] reading all frames in a multi-frame image

[Manuchehr Aminian]

URL:
  <http://savannah.gnu.org/bugs/?30365>

                 Summary: reading all frames in a multi-frame image
                 Project: GNU Octave
            Submitted by: manuchehr
            Submitted on: Tue 06 Jul 2010 10:11:35 AM GMT
                Category: Libraries
                Severity: 3 - Normal
              Item Group: None
                  Status: None
             Assigned to: None
         Originator Name: 
        Originator Email: 
             Open/Closed: Open
         Discussion Lock: Any
                 Release: 3.3.51
        Operating System: GNU/Linux

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Details:

In short: imread returns an error trying to read more frames than an image
has.  I'd like it to return all frames of an arbitrary multiple-frame image
(e.g. .gif, .tiff files) and store them in an array.

Currently, imread() supports reading multiple frames of a .GIF (say) image
using an optional second argument.  For example, if I know my example.GIF has
16 frames, I can do:

M = imread('example.GIF',7);

to read one frame, or

M = imread('example.GIF',1:16);

to read a range of frames (though this isn't in the documentation for
imread() at the moment).  However, if I do not know the number of frames in my
image, and tried to read the first 17 frames of my image that only has sixteen
frames,

M = imread('example.GIF',1:17);

Octave returns an error with no array.  This is really the problem.  If there
is not some way to do this already, the cleanest way I see to fix it is to
modify imfinfo to be able to detect the number of frames in an image (if this
is something that's in the metadata of GIF files, i'm not sure), then use that
to implement a parameter to read all the frames in imread, or if the user is
requesting to read frames that don't exist, return what can be read up to that
point.




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