[argyllcms] Re: How handle Lab tiffs?

Graeme Gill wrote:
...
The problems hint at some conceptual
issues as well. Problems that I notice are:

  The image gamut has no white and black point. I can simply assume
  in tiffgamut that an Lab image has white and black points of 100,0,0 and 
0,0,0,
  but there is a trap waiting if someone converts from a device
  space straight to Lab and doesn't ensure that the conversion
  also expands and maps the device space white and black to
  100,0,0 and 0,0,0

  There is a bug in tiffgamut that means that selecting CIECAM02
  output for compatibility with collink is being ignored. The resulting
  gamut will be in L*a*b* space.

  The gamut mapping code takes the number of guide points from
  the source gamut surface, and this depends on the surface complexity
  (number of facets) and shape. For the Lab space source, the surface is
  a cube with only 8 vertices so the number  of guide points, or for Jab
  it is stupidly large with facets in places that aren't relevant to the
  image gamut.

It should be possible to fix these various problems for the next release.

Graeme Gill.

By other words, the workflow "tiffgamut -> collink -> cctiff" can't operate 
properly? "There is a bug in tiffgamut" - is it only for Lab image case or it 
is the global problem?

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