Re: dot gain - still more
Re: dot gain - still more
- Subject: Re: dot gain - still more
- From: Graeme Gill <email@hidden>
- Date: Mon, 09 Feb 2004 13:44:15 +1100
- Organization: Color Technology Systems
Roger Breton wrote:
litho printed samples of 100% cyan and find the one that yields an L* of
about that value and read its corresponding density. Would that be valid? As
a matter of fact couldn't one find a statistical relationship between L* and
Optical Density? It may not be linear but I'm sure it would have a high R2.
Roger, there's no need to look for a statistical relationship, they are
directly related. The Y of XYZ is
optical reflectance, and L of L*a*b* is directly converted from Y, so
optical density is -log(Y/Yref).
(choose Yref depending on whether you want the density to be paper
relative, or relative to the
perfect diffuser).
Of course is you are after a "status XX" density, then XYZ can't be
directly used, since it's
wideband, and "status XX" densities are narrowband measurements. You
might get away with
using the Y value as a good guide though.
Graeme Gill.
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