Re: Jpegs and GNO

[o9938156@unicorn.it.wsu.edu (mark lyon)]

Dan Masterson (dmasters@freenet.columbus.oh.us) wrote:

: I've been trying to convert some JPEGS to GIF using DJPEG under GNO. 
: However I keep getting a message that I'm out of disk space (not when I've
: got 4 megs free on the partition).  The JPEG is over 60k.  I've had
: success converting one under 45k.

: Could this be a bug in DJPEG or do I need to increase my ram disk to
: beyond 1600k?  Does the -maxmemory function work under GNO?

: Any help would be appreciated.

I'm assuming that you're using the port of djpeg version 6.  I can't
say if any of this will work on an earlier version.

It's not the size of the JPEG file that matters, it's the size of the
image itself.  A 60k JPEG file could easily be a 800x600 pixel image.
Anyway, djpeg makes use of temporary files that have to hold the entire
image when decompressing into a GIF.  These files can be quite large
(about 1.4 megs for a 800x600 pixel image).  I think that these files
are also stored in the same directory that contains djpeg, so even
though you may have plenty of free space on one partition, if the 
partition that contains djpeg is getting full, you might run out of
disk space.

I can think of a couple of things to try.  First, unless you have some
important reason for having a RAM disk, I'd get rid of it, and try

djpeg -maxmemory 3500 image.jpg image.gif

(assuming you have 4MB of RAM in your GS).  This way, djpeg might be
able to do without a temporary file.  If that doesn't work, check the
disk space on the partition that contains djpeg.  Clear up a few MB
if you can (or move djpeg), then try decompressing it.

If that still doesn't work, try either

djpeg -scale 1/2 image.jpg image.gif
or
djpeg -onepass image.jpg image.gif

The first will give you a half size image and the second will use
a one pass color quantization method which will give you reduced
image quality.

Hope this helps!

Mark Marr-Lyon
o9938156@unicorn.it.wsu.edu

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