[Openicc] Re: color-policy vs. color-infrastructure

[Stefan Döhla]

>> How do you obtain an exact inversion? And how does that relate to the
>> gamut?

> By representing the colorimetric A2B table in memory, and inverting
> each cell (along with the per channel tables etc.). Another way
> of putting this is that the A2B table is searched for a device
> value that gives the target PCS. If no device value is found,
> the PCS must be out of gamut.

But is this information really helpful? In real applications I don't
want to know, whether a color is printable by setting a (unknown)
particular color.

What I really need is
the information, whether a particular color is reproducible, by
setting it's values e.g. in Lab. Can you tell me, what color should
have been selected in the app to get the desired color?

For real color management it should be the same color, which isn't
guaranteed if you're only checking the A2B table.

To see, whether a PCS color was preserved, the B2A table must be
considered.


Your method can work only if A2B is truly the inverse of B2A,
which means, there happens no shift. This is something, I wouldn't
assume ...

Stefan

-- 
Stefan Döhla
mailto:color at doehla.de