Dan Williams wrote:
On Mon, 2007-03-12 at 03:22 -0400, Albert Cahalan wrote:
Long ago, Tux Paint used 5:6:5. This caused colors to get messed up if
the user did repeated blur, smudge, pixelate, and similar operations.
Tux Paint normally uses 8:8:8 RGB, with occational 32:32:32 (linear float)
RGB for troublesome blending operations like smudge. The version that
runs on the B2 OLPC XO is currently using 5:5:5, but this causes lots of
conversions that require bit shifting. The situation would be much better
if the XO used 5:5:5 or 8:8:8. While 8:8:8 is 50% bigger, it avoids lots
of bit shifting (very slow on many processors) and preserves information.
You're completely correct.
Eliminating the use of 32:32:32 will probably involve linear integer data,
16:16:16 on normal hardware at least, perhaps with MMX via gcc's vector
support. This wouldn't be 5:6:5 either.
If I recall right, eToys was using 5:5:5 and GDK uses 8:8:8.
Switching to one of those would be good. 5:6:5 can't even do grey.
Not that non-linear data is any good for computation...
Sugar doesn't really use GDK, it uses hippo-canvas and cairo. But
neither cairo or GDK really work well at 555.
LiVES uses GDK internally, so it would have to be added as part of the
LiVES port.
Regards,
Gabriel.
http://lives.sourceforge.net
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