Re: How to objectively measure quality of print profiles?
Re: How to objectively measure quality of print profiles?
- Subject: Re: How to objectively measure quality of print profiles?
- From: Harold Boll <email@hidden>
- Date: Fri, 03 May 2013 17:23:56 -0400
> http://www.youtube.com/watch?v=sTxaHhMYSYE
Interesting video; I like that they emphasize the need to consider 2 gamuts:
a proofer gamut (A2B1 Tag: device coordinates ->Lab direction) and a
rendered gamut (B2A1 Tag: Lab -> device coordinates).
The original poster of this thread mention 'gamut volume' as a quantitative
measure of quality, but that criteria has to considered judiciously. For
proofer gamuts, bigger (greater volume swept out by the transform) is always
better; it should be a reflection of the native gamut of the hardcopy device
that was characterized by measurements. But for the rendered gamut, bigger
is not necessarily better - ideally, there is an optimal volume that lies
between max volume and a much-too-small volume. The two gamuts should match
up above the cusp (max chroma at given hue angle); but below the cusp, the
rendered gamut should be somewhat inside the proofer gamut if the profile is
any good. There are basically two reasons for this; the less important one
is that constraints (TAC, ink limits, etc) imposes a smaller gamut. But the
more important one is to preserve smoothness and continuity in the inks as
you move toward the shadows. If you maintained a max gamut below the cusp,
then small variations in color (Lab space) would result in large variation
in inks. This would wreck havoc with shadow detail.
Harold Boll
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"Keep it simple, but no simpler!"
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