[argyllcms] Re: Camera Profiling using ArgyllCMS

  • From: Nikolay Pokhilchenko <nikolay_po@xxxxxxx>
  • To: argyllcms@xxxxxxxxxxxxx
  • Date: Fri, 28 Nov 2008 17:51:11 +0300

> > I think the non-linearity of "RGB" (most likely LMS) data from sensor must 
> > be
> > compensated before matrix conversion to allow the next conversions to be 
> > truly additive
> > nor multiplicative.

Graeme Gill wrote:
> It's hard to guess what typical raw tools workflow actually is. Some may
> attempt to do white balancing prior to ICC based color space conversion,
> although any such variables will tend to invalidate the profile. Personally
> I'd be looking at creating a workflow in which the ICC profile
> is used to convert the raw input into absolute XYZ space, and
> then apply rendering effects such as white balance etc. in XYZ space.
> For this purpose, a matrix profile may be a better bet than
> typical CLUT profiles, since CLUT profiles may not have the required
> accuracy over a raw images full dynamic range.

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.

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