[Ids-devel] The trouble with PNG and gamma correction

[Arshad T. <ars...@sl...>]

Hi,

I'm still enthusiastic about IDS on the Mac, but haven't had as much 
time as I'd hoped to play with it.
I've been working on a great new theme based on polaroids I saw taped 
to a wall at a party recently.  It looks great - but the PNG generated 
album thumbnails look very inconsistent across browsers (at least on 
the Mac).

Here are a couple of screenshots (you can see it's a work in progress, 
and I started with the PhotoCorners theme).
Album View: http://www.slackers.net/~arshad/ids_shots/idsroid-album.jpg
Main Page View: 
http://www.slackers.net/~arshad/ids_shots/idsroid-lib.jpg

Main Page View on IE 5.5: 
http://www.slackers.net/~arshad/ids_shots/ids-ie.gif

The problem is that PNG is a format that implicitly support gamma 
adjustments.   And when no gamma is provided in the PNG image, the 
browser that renders it decides what default gamma correction to apply. 
  Different browsers decide on different adjustments, theoretically, to 
match the canonical sRGB color space, so that the colors appear the 
same on different monitors/platforms/computers.  However, this gamma 
adjustment is performed on the PNG, but not on the entire HTML page.  
So if you want your PNG to blend in  with the surrounding HTML, you 
will get different results on different browsers!

Here are some more samples I've done to illustrate the PNG problem:
http://www.slackers.net/~arshad/pngprob/pngprob.html  (included is the 
sample with 4 color tables, and 3 screenshots of the dominant Mac 
browsers).

Any ideas on how to best address this problem?  One thought I had was 
to use ImageMagick to transform the resulting album PNGs into GIFs as 
wll, and use the GIFs (I haven't used ImageMagick before, but I assume 
that's possible).  Any other ideas?

Also, when I finally finish this - should I submit my theme to be 
included in the next release?  (I have other grand ideas too, but not 
as much time as I'd like to work on them).

Thanks!

-Arshad