[Openicc] Xorg low level buffers - colour conversion

[Tomas Carnecky]

Hal V. Engel wrote:
> On Saturday 08 March 2008 07:22:52 Tomas Carnecky wrote:
> GLEW, http://glew.sourceforge.net/, is currently being used in the panorama 
> blending program enblend.  Taking a quick look at the GLEW web page it 
> appears to be a library to assist programmers in optimizing their OpenGL 
> code.   On my machine moving from a version of enblend without GPU support to 
> one with GPU support (using GLEW & OpenGL) cut enblend times by about 90%.   
> The first time I ran this I thought that something had not worked because 
> there was no way it could be that fast.   I have a fairly high end but 
> slightly older GPU (NVidia 7950 GT) and I suspect that the amount of speed up 
> is dependant on how many pipe lines the GPU has (mine has 24) as well as how 
> fast these are.  A state of the art GPU would likely be significantly faster 
> still.

For the color conversion with shaders, your limiting factor will be the 
pixel fillrate. It's currently in the order of 1-15 Gigapixels per 
second. You can look up at wikipedia how big the fillrate is for various 
graphicscards. It's interesting that the fillrate varies even among a 
single chip generation: the slowest GeForce 8 does ~2 Gigapixels/s, the 
fastest about 15. I suspect that the newest GeForce generation (unveiled 
just last month) will be able to do at least 20. According to the 
wikipedia article your card does about 13 Gigapixels/s, so it's 
definitely one of the faster cards.

tom