<http://lipas.uwasa.fi/ktt/lasktoim/photo/phtest/phtest.html> Copyright © 1999-2005 by Prof. Timo Salmi Last modified Sun 6-Nov-2005 07:02:22

Testing Publicly

The original thumbnail 1609 bytes

Without the ppmquant 256 1622 bytes

rec.photo.digital #190118 (1 more)
From: ts(a)UWasa.Fi (Timo Salmi)
Subject: Re: Wind energy
Date: Thu Jun 24 07:48:57 EET DST 1999
Organization: University of Vaasa

In article [uo9yahawg4a.fsf@netcom13.netcom.com],
Tom Lane  [tgl(a)netcom.com] wrote:
:ts(a)UWasa.Fi (Timo Salmi) writes:
:>       djpeg -pnm < ${f} \
:>        | pnmscale -ysize 60 \
:>        | ppmquant 256 \
:>        | cjpeg > tmp.$$.jpg

:Omit the ppmquant step, and you'll probably find that the resulting
:files are both smaller and better looking than before.  They'll

Dear Tom,

Thank you for the interesting tip. I made one random run coverting a
58825 byte jpg FD-71 digicam image file. When the ppmquant 256 step
is included the resulting thumbnail is 1609 bytes. When the step is
omitted the size is almost the same, i.e. 1622 bytes. In this case
the size slightly grew because of the omission. I have Windows 3.11
and Netscape 4.03. I can't visually detect any obvious quality
difference.

   All the best, Timo