[argyllcms] Re: icmColorantTableVal_write: write of PCS coord failed

Gerhard Fuernkranz wrote:

Looks like the major issue is caused by the B2A tables, though I don't
fully trust the A2B1 table either - the self-fit error is IMO
unreasonably low (I think I need to run a cross validation with separate
training and test sets to assess).


It could just be that XYZ space is a better match to the device,
which is quite possible given the mainly additive nature of
displays.


So I'm wondering, couldn't it be useful to make use of the matrix in the
lut16type in order to extract the "RGB cube" from the XYZ space? I.e.
find the smallest triangle in [x,y] chromaticity space which completely
encloses the device gamut (projected to [x,y] chromaticity space), and
setup the matrix in the lut16type so that it maps XYZ to the (linear)
RGB space described by this triangle. These RGB numbers are then fed
into the prelinearization tables, etc. I guess this could significantly
reduce the subset of the XYZ space which needs to be covered by the CLUT
table.


Yes, that would be ideal. I haven't figured out how to make that work
with the per channel curve creation logic though.

cheers,
        Graeme Gill.

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