Re: Linear-light RAW 12bit vs R'G'B' 8bit: how much better is it really?
Re: Linear-light RAW 12bit vs R'G'B' 8bit: how much better is it really?
- Subject: Re: Linear-light RAW 12bit vs R'G'B' 8bit: how much better is it really?
- From: "email@hidden" <email@hidden>
- Date: Tue, 24 Jul 2007 17:26:35 -0500
On Jul 24, 2007, at 4:54 PM, Ray Maxwell wrote:
I don't know how you would express the gamma of a solid ink on
paper??? I can't help here. However, I do know that the original
Apple Postscript Laser Printer did print with a gamma of
approximately 1.8 due to the screening used in this printer. With
screen calibration LUT's you can make a printing system print at
any gamma.
Maybe I don't have the right idea about gamma. As I understand it, it
is an expression of the non-linearity of a function or system. So,
you wouldn't express the gamma of a solid. You would, however express
the gamma of all the steps from no ink up to the solid.
The Neutral Print Density Curve is not straight, it is curved. The
density increases in a non-linear fashion.
The other possibility of where this might have come from, is that
when printing with modern CTP systems you lose the dot gain that
comes from imaging a plate from film. This is usually equal to
about 5%. This means that a typical CTP system has an end to end
dot gain of about 15% to 18% at 150 lpi. Most printers put in a
LUT to correct this back to the more normal 20% to 25% dot gain so
that they can print legacy files. At the higher dot gain the
system is more visually linear and close to a gamma of 2.
You're killin' me, Ray! :-) You say that you don't know how to use
gamma in discussing ink on paper, then you use gamma in discussing
ink on paper. Is there a secret society of Gamma Dudes? Are you guys
like Masons, or something? This seems like a very carefully guarded
bit of urban legend.
Rich Apollo
G7 Certified Expert
Adobe Certified Expert, Photoshop
314-344-1144
email@hidden
www.prioritylitho.com
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