Nikolay Pokhilchenko wrote:
It's exactly what I dream about! You are "hit the mark"! I think the RAW channel data can be linearised equivalently at a stage before conversion to XYZ because of camera design. I suppose there will be enough simple matrix conversion to XYZ after linearisation without any LUT. That profile will be most exact because of it may be physically natural and correct.
That's one approach, although profiling using a test chart, particularly one composed of real world spectral samples, leaves other non-linear possibilities though. The basic issue is that if a sensor has spectral sensitivities that are not a linear transform of those of a human observer, then it simply doesn't see the world in quite the same way, and a single matrix transform may not be the optimal way of making it approximate a human observer. If something is known or assumed about the statistical distribution of different colorant reflective spectra being photographed, then it may be better to (effectively) use different transform matrices for different colors. A CLUT based profile has an equivalent effect. Graeme Gill.