Frank writes ...
> > As Frank implies
> > ... there is a separate Lab defined for each illumination ...
e.g.,
> > subjects illuminated under D65 vs D50. Not a big difference,
>
> .... Once the eye becomes
> accommodated, it shouldn't notice a difference between the two
lightings,
> but to see that in fact there is a considerable difference, try
switching
> your monitor between these two temperatures. You'll see a pretty
distinct
> difference.
The "small" difference I was referring to is ... converting from
one space to another, D65 v D50, is I believe a single variable in a
transform function.
> But all this is an aside. I didn't quite understand the points
> you were trying to make in your latest post, ...
The important points (other than humbled by a blunder) were:
1st point ... relative to Photoshop color spaces, I now understand
RGB is relative, and it is possible to create a profile for which you
may find 0-0-255 in your gamut.
2nd point ... one should never hope to find 0-0-255 in your gamut
because it would imply you have very little room to edit your "blue"
component.
sidelight point ... if you never want 0-0-255 in your gamut
because of lack of editing overhead, then as you approach perfect
devices and the wide gamuts associated with them, then 0-0-255 should
approach a "perfect" blue ... a "concept" blue ... a "nonexistent"
blue.
Last point, really a question ... the blues our eye perceive have
somehow been translated into computer a (mathematical) transform.
That is, someone extracted "blue" from the spectrum of photons, and
defined a physical reference point and a transform for computer
display. I wonder if it isn't the CIELAB (L*a*b) definition ... that
is, other Lab spaces seem (?) to be relative to L*a*b.
Next question ... can we bring this subject back to film scanners,
and their ability to capture the gamut of film (my golden fleece).
shAf :o)
