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[Nick Bannon]

On Thu, Oct 12, 2000 at 09:14:09PM +0800, Leon Brooks wrote:
> Ah. Time to buy a bigger camera then. (-: Only 500KB/frame with the current one
> :-)

Ah, speaking of that... ::-)

I find a lot of the photos out there seem to be huge in size - trying
to absolutely minimise the loss of quality due to JPEG compression. A
fine goal to be sure, but a little painful when seen from the wrong end
of a modem link.

QUALITY=75
for i in *.jpg; do
  TMPFILE="$i.tmp$$"
  djpeg "$i" |cjpeg -quality $QUALITY -optimize -progressive > "$TMPFILE"
  mv "$i" "`echo $i | sed 's/\.jpg$/_orig.jpg/'`"
  mv "$TMPFILE" "$i"
done

I find this will reduce filesizes by over a factor of two with very
little visible difference. 75 is the default cjpeg setting - 80 and 90
still save space and are almost indistinguisable from the originals for
virtually all source images coming out of a digital camera, and
depending on the image, you can go down a bit as well.

The progressive option is pretty space-neutral, but also makes the
experience more pleasant.

As for thumbnails - you can get good results by simply lowering the
quality rather than scaling down mercilessly. (say scale down 4:1,
quality 10) On these sorts of images, you end up with something 

-- 
  Nick Bannon  | "I made this letter longer than usual because
nick at it.net.au | I lack the time to make it shorter." - Pascal