[SDL] Blitting algos...

[Simon]

> The human eye cut of is at about 10bits per component without the need 
> for lighting corrections and at 12 bit's per component for lighting 
> correction or colorspace conversion. So the 10,10,10,2 RGBA format is
> quite adequate. SDL 1.3 has support for the pixel format above.
> I'm not sure if 1.2 supports bigger than 8 bits per component formats 
> though.

The reason I need more than 8 bits per colors is for rare instances, the 
one I see clearly right now is for heightmap, where one component 
(grayscale) needs to have more than 256 degrees of elevation, in this 
case 16 bits is very good and gives a smoother landscape.

But I've started using all of what an image can provide and thus on a 
give mapfile (a png for example) it can contain the height map on the 
red color, vegetation information on the green (types and quantities in 
this pixel area), water information on the blue, atmospheric effects on 
the alpha... etc...  In this case it might be interesting to have a 
different amount of bits for each component, as some require more 
precision than others.

Of course, imo, when going higher than 8-10 bits per pixel, the image is 
no longer for the human eye, but as many of you pointed out, it is 
rather for the computer, for its calculations and gives more precision 
to the result of those calculations.

Thanks,
   Simon