From mboxrd@z Thu Jan  1 00:00:00 1970
Message-ID: <14ec7b180604262336k4317659dl1e3d4710580d8cc6@mail.gmail.com>
Date: Thu, 27 Apr 2006 00:36:13 -0600
From: "andrey mirtchovski" <mirtchovski@gmail.com>
To: "Fans of the OS Plan 9 from Bell Labs" <9fans@cse.psu.edu>
Subject: Re: [9fans] PNG and APE (cntd)
In-Reply-To: <36acd81591ae44aee30ef39313a71dfd@proxima.alt.za>
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> I have a slightly OT question: is it reasonable that PNG versions of
> an image may be bigger than their GIF equivalent and (less
> sursprisingly) much bigger than their JPEG versions?  I have not
> tested this theory, but I have had this reported to me.

png is libz compression, so even at its best you can still have an
image that compresses very badly. in fact i think i have an example,
let me find it... here:

http://pages.cpsc.ucalgary.ca/~mirtchov/screenshots/scr-porcini.png

basically that image (an album cover i used as as a desktop
background) even though small in acreage is large in size as a png
(1.1 megs) at compression of 9 and there's nothing we can do about it.

i don't care much about gif, but JPG achieves the small file size by
being lossy. for a test open up a JPG image in gimp or whatever editor
and save it again, but increase the level to 100% (instead of the
usual 85 or 90):

-rw-r--r--   1 andrey  andrey  1125261 Apr 27 00:28 IMG_3735-1.jpg
-rw-r--r--   1 andrey  andrey   446941 Apr 26 17:18 IMG_3735.JPG

(the images are otherwise unaltered)