Hi Graeme, > in theory the RGBA case could be handled as a normal color lookup using a 4D color tabl
Yes, you are right. That could be possible (even if this is beyond my skills as it would mean digging deeper into LittleCMS optimization engine) but as you pointed it out, in practice, it may not be a good idea. I'm thinking about the accuracy loss because of alpha normalization (only in 8 bits/channel). For a example, for an opacity of 20%, alpha would be 51 and all channels would be normalized in [0..51] range. In such discretized space, a conversion from sRGB to some screen color space could even by identity (or will be far from accurate)... Having a huge 4D Lut and not using a big part of it would be frustrating ;-) > and vector instructions are rather fast in modern CPU's. My tests shows that this extra work is as costly than the matrix calculation... So this is still some time but if I double this code with SSE version, I'm pretty sure that it won't be a problem anymore. Boudewijn Rempt gave me recently a link to a vectorization library (http://code.compeng.uni-frankfurt.de/projects/vc) and I doubt I could resist too long before I try vectorizing the premultiplied code ;-) Best regards Sebastien ------------------------------------------------------------------------------ LogMeIn Rescue: Anywhere, Anytime Remote support for IT. Free Trial Remotely access PCs and mobile devices and provide instant support Improve your efficiency, and focus on delivering more value-add services Discover what IT Professionals Know. Rescue delivers http://p.sf.net/sfu/logmein_12329d2d _______________________________________________ Lcms-user mailing list Lcms-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/lcms-user
