PNG support (was Re: [HIG] Mini-Guidelines style)

[Christian Rose <menthos menthos com>]

Calum Benson wrote:
> > Do we want to be PNG purists here?
> 
> Being pragmatic, I'd say 'no', because we got a shedload of complaints
> from people who read our initial draft of the usability report for whom
> some PNGs wouldn't display properly (NS 4.x on Solaris, and IE-anything
> on Windoze), and we ended up having to re-do most of them as GIFs or
> JPGs.  So whilst I agree with the sentiment, it might end up causing us
> extra work.

Hi everybody, and good luck with the mini-HIG work. I just wanted to
mention my opinion regarding the topic of using PNG:s or not.

I'd say "yes". Yes as in "PNG:s should be used". Yes, some png:s
(usually png:s with alha channels in my experience) can display
improperly on some older browsers with broken png support.
However, that does not change the fact that the gif format is usually
loaded with patent problems, and that GNOME is part of the free software
movement and has a policy against software patents and thus the use of
the gif format.

It also doesn't change the ability to usually fix this problem at the
png level - as mentioned, most browsers crappy support for pngs has to
do with png:s with alpha channels (gimp by default saves png:s this
way). If you are not on purpose doing a transparent picture, the alpha
channel can be safely removed. An excellent tool for this is convert
(part of the ImageMagick software package). Just run

	convert file.png file.png

and you will in many cases end up with a png image that displays a lot
better in Netscape 4.x and the kind.

Granted, I don't know what the exact problems were with the png:s in the
usability report, but I think that rather than dismissing the png format
altogether, it should be investigated if this would solve the problem.


Christian