"Rick (Kitty5)" wrote:

> Yes but as I pointed out a couple of days ago, PNG images are displayed
> differently depending on what software is used, forget any ideas you had
> about gamma correction with a PNG.

True. At the moment, things are a bit of an issue. But the situation is
improving quite rapidly. Once you figure out how things are really working (i.e
which of your programs display PNG images correctly and which mangle them and
how), then one can start to get a lot better than with using BMP or TGA.

Although I have very realistic ideas about gamma correction with PNG (being a
programmer delving in the graphical realms for ten years now) that don't really
need to change. However,  the warning is a very good one that should be put out
for all those who don't read the PNG specs and follow the developer mailing
lists.

To Sum up: BMP and TGA loose all Gamma information, and the end viewer has to
guess what was intended.
PNG stores the Gamma information, _BUT_ not all programs handle this correctly.
In addition, not every image author has his system setup correctly.

Suggestion: all those who are interested in viewing PNG images should test
their different software with the images at
http://www.cdrom.com/pub/png/pngsuite.html
In had with the gamma file at http://www.povray.org/ , all of us can start to
get to see the artistic intent much better.

(BTW, Bad news: Netscape Navigator 4.51 does not handle the gamma correctly,
and just dumps the raw pixels as-is. (then again, that's the situation you have
with JPG, BMP, TGA, etc.)

> Personally I use a lossless raster format for storage, such as a BMP or TGA,
> and do the compression myself.

That's probably fine, but you might be missing out on some minor benefit. A PNG
version of the you sent me was 12% smaller than the ZIPped BMP version (574K
instead of 655K).

Oh, and as far as the content of the PNG over the JPG... WOW. Huge difference,
and great image!

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