[Gimp-developer] jpeg quality factor.

[Robert L Krawitz]

   From: Sven Neumann <sven at gimp.org>
   Date: Sun, 08 Jul 2007 23:48:28 +0200

   On Sun, 2007-07-08 at 18:31 -0300, Guillermo Espertino wrote:

   > What I didn't know (and wouldn't expect) is that Gimp will
   > destroy my pictures without warning me.  And that's exactly what
   > I get.  I have a picture taken at 95, open it and save it, and it
   > ends up at 85.  Why is that?

   Because you are using JPEG despite better knowledge that it will do
   exactly that. Sorry for the harsh tone, but I am only replying the
   way you are putting it.

Sven, I do think you're being unreasonably hard on Guillermo.  Never
mind that using JPEG per se won't "do exactly that" -- what's really
degrading the quality so badly is GIMP's choice of a quality factor
compared to that of the original JPEG.  Not to mention that I think
Guillermo is being quite reasonable.

A lot of people (particularly folks who just casually want to lighten
a shot or remove redeye) don't know it.  All they know is that they
have a picture that their camera took, they've corrected it, and all
of a sudden the image quality fell apart.  They don't know anything
about JPEG's, or compression (lossy or otherwise), all they know is
that GIMP ruined their photo.  That's not going to be very helpful to
anyone.

   I already explained that the JPEG plug-in cannot access the
   settings that were used to save the file. We can also not easily
   change the code to always show the settings dialog because then we
   would have to do show the dialog for all file plug-ins. There might
   be a way out of this, but there is certainly not an easy one. So
   please calm down and let the developers deal with this. After all
   this is a developer list. Your harsh comments are not helpful.

Well, as was noted ImageMagick is able to access this information, so
it's apparently there.  Maybe this isn't going to be an easy problem
to solve, and that's OK, but I think that this is a real problem, not
simply a user error (and even if it is a user error, wouldn't it be
best to help users not make this kind of error?).

-- 
Robert Krawitz                                     <rlk at alum.mit.edu>

Tall Clubs International  --  http://www.tall.org/ or 1-888-IM-TALL-2
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"Linux doesn't dictate how I work, I dictate how Linux works."
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