Hi Mick, 

As much as I like GIMP, there may be an easier/faster way...

use jpegtopnm, pnmtopng, and cut. should look something like...

for f in *.jpg; do jpegtopnm $f > /tmp/tmp.pnm; pnmtopng /tmp/tmp.pnm > `ls $f | cut 
-f 1 -d "."`.png; done

not tested and I'm a little rusty but i processed a lot of images in this way 
for a user study I did for my dissertation.



   Mailing-List: contact [EMAIL PROTECTED]; run by ezmlm
   From: Mick Raynes <[EMAIL PROTECTED]>
   Date: Thu, 25 Jan 2001 13:39:13 +1000
   Content-Type: text/plain;

   Can anyone offer us assistance with converting/saving a jpg image as png?

   We have around 5000 images which come in at around 150kb each.  We are
   hoping to convert the images to png because down the track we are hoping to
   convert them to thumbnails on the fly.  The images will only be presented on
   the net (assume browser capability)and it is pretty important that we retain
   colour and shadow integrity.  We have limited experience with Gimp however
   we are pretty confident that it will fit the bill and that once we determine
   the process we will be able to batch convert the images.  The original jpg's
   are not all in the same format as they are taken with different digital
   cameras with different settings.  Our aim would be to reduce the original
   jpg 1000 by 1000 and 120kb (as an eg) to a png 500 by 500 and about 30kb.
   As an example we have posted an original jpg image on the net at


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