CKMY craziness...

[Saem Ghani]

On Monday 22 November 2004 10:47, Boudewijn Rempt wrote:
> On Mon, 22 Nov 2004, Cyrille Berger wrote:
> > how fast (or slow) is it to change from a color space to an other one ?
>
> Not that bad, it depends a bit on the colour space -- cmyk is a fair bit
> slower than gray or rgb. It's basically another filter that needs to
> handle every pixel, so much is dependent on the effciency of iterators
> or other ways of accessing pixels.

If I understand it correctly, it's actually quite costly.  You iterate over 
the entire image and unless it fits in cache -- unlikely -- it's going to run 
very slowly since you're going to be bound by the system bus, even though 
it'll be streamed over and be efficient as memory accesses go, there are 
really no cache wins so it's something worth avoiding/optmizing.