Image compression and its possible future in Quake 2

[Karen Pouelle]

I said, "If you want a PNG texture pak, let me know - but it will be twice
the size and probably less than twice the quality improvement."

Then danfe replied, "You might want to take a look at OptiPNG (OptiPNG is a
PNG optimizer that recompresses the image files to a smaller size, without
losing any information)." 

I wish you would have told me this sooner! :) Last month I optimized all the
PNG's in the CVS and got a savings of 3% to 25% percent.  In addition, the
utility also corrects some common warnings that libpng spits out, simply by
re-encoding the PNG correctly.  Without it, the ratio of png to jpg (At
highest quality setting) file sizes would be closer to 3 to 1.  I'm in the
process of rescripting for PNG pak creation with the CVS's fully optimized
png's which I estimate will be twice as big as the jpg pak. The
fully-compressed png's, like the highest quality jpgs, don't compress well,
so I won't be archiving the pak files in either format.

I'll eventually (next few days, probably) provide png pak files for those who
want it, but please read the faq there at least once even if you know what
you're doing, no matter which you choose. Any constructive feedback is
welcome.

I added some reference screenshots, but the best benefit to retexturing is
when you get within 3 scale feet of a wall - its texture shows much better
than the originals. I'll eventually throw in some other screenshots in there
as well.

Once I get the jpg and png paks in place, I welcome reference screenshots of
jpg vs png as Quake 2 textures for comparision.  While I fully support PNGs
and understand the limits of jpgs, at Quake 2's current state, there is going
to be little visible difference between the two.  I've opted to provide paks
for both, but still think the size per quality ratio goes to jpgs (So does
the Quake 2 Evolved project, which is not supporting PNG's in their engine AT
ALL!).   

For archiving images, nothing beats PNG's!

As far as lossy formats go, for your own edification I wish to present to you
S3TC compression.  You've probably seen the option to turn on texture
compression?  This is the format that your OpenGL cards are using. Currently
in development for future Quake 2 clients is the option to load the S3TC and
DDS textures.  But of course, PNG's (totally lossless) will always be
superior in quality!

S3TC seems to beat out jpeg in "real world" applications for quality per
kilobyte.

http://www.digit-life.com/articles/reviews3tcfxt1/



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