From: Alberto Novo (alnovo@inwind.it)
Date: 09/20/02-12:03:14 AM Z
> I made a ramp from zero to 100% in Photoshop, then posterized it into
21
> steps.
> (Even if you did this at 5% and 95% I doubt results would be much
> different.)
> So here's my question:
> Why does it print fewer steps -- on each of 5 substrates I'm testing -
-
> than the Stouffer 21-step I'm printing next to it.
> And I mean by about a third.
> Judy
The ramp from 0 to 100% is not equal to a ramp od density: from 0 to
0.3 D the Photoshop ramp goes from 0% to 50%, from 0.3 to 0.6 D it goes
from 50% to 75%, and so on. That is, each 0.3D halves (or doubles) the
blackness.
Moreover, I have also found that a "correct" negative (0%, 50%,
75%,...) does not shows the "correct" densities, and needs some other
refinements based on these results. These last depends on printer,
inks, and transparent/paper.
Alberto
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