jim feldman <jmf <at> jim-liesl.org> writes:

> >  (No lectures on the default 85 being "enough", thank you - it is not
> >enough, and I can clearly see artifacts on my edited digital photographs if
> >saved with 85.).
> I assume your camera is outputing jpeg.  Does it have a raw or tiff 
> output as well?  The raw you'd have to drag through a converter thats 
> specific to your camera, but you could probably write that out to tiff.  

  I already got my answer, and have pointed these out in another post, but...

  Powershot G3 and Canon EOS digital cameras do output RAW. Unfortunately, this 
is not an option (currently) because RAW format is more or less proprietary; 
All the information on the shooting conditions (that is stored in standard EXIF 
when saving to JPEG) is in some weird bit pattern that needs to be reverse-
engineered. There are partial solutions that work under Linux, but for now, the 
only tool is Canon's own Windows (or Mac) software. And at least the Windows 
software (Zoombrowser ex) - well - sucks for batch conversion.
  Granted, the EXIF information can usually be extracted from .THM thumbnail 
files (they are standard JPEGs). Still, I'm not sure if I can trust OSS tools 
interpolation algorithms - if they are not up to par there could actually be 
loss of quality compared to JPEG due to interpolation artifacts. I tried these 
(craw or something) about a year ago, and was not satisfied with the results 
back then. Haven't checked on progress, though.

  Anyway, the final (archival) format needs to be JPEG, because it's the de 
facto standard. I can archive my photos to CD, and that CD can be read by any 
computer with any OS, my DVD player, even cellphones. And all the shooting 
information is readily available in EXIF headers. JPEG also has the comment 
field (both in an outside of EXIF). So everything is nicely stored in a single 
file that also happens to have a compression algorithm optimized for 

  I have set my JPEG compression settings in my camera to "superfine", which 
produces about 2 MiB files on average. This corresponds to quality setting of 

  The "optimal" solution for me would be if I could get a (good) RAW-> JPEG 
2000 converter. JPEG 2000 would have the EXIF strutcture intact, lossless mode, 
and it will (probably) also be supported everywhere. However, this cannot be 
done at the time because of patent and licensing issues slowing down the 
adoption (and the lack of RAW converters that I could trust). Maybe in 2010.

  Oh, and there IS a difference Q=85 <> Q=95 <> Q=98 - this is not some "seeing 
what you believe you are seeing" or placebo effect. I'm NOT going to set up 
comparison web page to prove a point (you can easily do that yourself - take a 
picture of something that has lots of small details - say, ice crystals or 
small insects with a macro lens), but when you have a 3000x2000 pixel 
photograph and you want every pixel count the difference can be clearly seen. 
Maybe not on a web page, but when printing wall posters or trying to display 
your photo collection on a big screen. The most obvious effect is a "halo" 
around edges; Also, all the small details (such as hair) seem to grow flippers 
between them. 

  As for the waste of disk space - as has already been said, the camera 
produces 2 MiB JPEG files - and so does Gimp (or cjpeg) at Q=98. No space 

  My "normal" use is not web use. My "normal" use for JPEGs is photo archival 
with highest detail possible within reasonable convenience (so this is why JPEG 
and not RAW or TIFF). All my friends and family who I share photos with have 
broadband connections (between 1-10 Mbps), so sharing photos is not hard. Also, 
even with these file sizes, I can fit around 2000 photos on a single DVD-R 
(which cost less than 1 euro), so here you go..

  I hope my points are finally clear. I already received my answer on upcoming 
gimp 2.4 features, and did the little patch to jpeg.c, so I don't see any point 
in continuing this discussion (except on when gimp 2.4 release is to be 

  Thank you.

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