imread on large tiff

[John Hayes]

Hi all,

I have a problem where if I try either imfinfo or imread on a 640x540x1800 TIFF 
file that is ~1.2 GB, Octave hangs seemingly indefinitely. This is occurring 
with both GraphicsMagick 1.3.18 and 1.3.19. I’m on OS X 10.6.8 with gcc 4.8.2 
(I built) and octave 3.8.0 downloaded on Dec. 27, 2013. I’m using the filename 
as argument to imfinfo and for imread, I use this:
> video=zeros(numFrames, numRows, numCols, 'single');
> disp('Reading movie file...')
> for i=1:numFrames
>     disp(i);
>     video(i,:,:)=imread(fileName,i);
> end

At least for imread, it seems to be hanging somewhere in the __magick_read__ 
function, but I haven’t dug into it too deeply yet. I’ve extracted the first 10 
frames of the TIFF using ImageJ, moved it into the location of the big file, 
and reran the script on this file. In this case, they seem to work. This 
suggests the problem may not be that it’s hanging but that it’s just going 
really slow. But it’s not immediately obvious to me why imfinfo would be so 
slow (or imread for that matter).

Btw, GraphicsMagick was configured with the following command:
> ./configure --with-quantum-depth=32 --enable-shared --disable-static 
> --with-magick-plus-plus=yes

As a final note, when I Ctrl-C to stop Octave, it takes a long time to actually 
quit. If I hit Ctrl-C multiple times, Octave reports the following:
> ^C^C^Cpanic: Interrupt -- stopping myself...
> attempting to save variables to 'octave-workspace'...
> ^Cpanic: attempted clean up apparently failed -- aborting...
and dumps a HUGE core file to /cores/ (>6.5 GB!!). In the process of writing 
the core file, it clearly affects the general I/O on the computer (to the 
extent I often have to reboot as sudo kill -9 won’t stop it), so there seems to 
be ‘something' gobbling up a lot of memory. :)

Thanks for any insight you can provide on how to solve the main problem 
(imfinfo/imread usage with a 1.2 GB TIFF). Any clues as I dig deeper would be 
most helpful...

Best regards,

John