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: Ray Maxwell <email@hidden>
- Date: Tue, 24 Jul 2007 16:32:10 -0700
email@hidden wrote:
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.
I will try to make myself more clear. You cannot talk about "ink on
Paper" as though that specifies any kind of printing standard.
First in order to talk about the word "linear" you have to be talking
about ploting some input condition to some output condition. If the
function in linear that plot will be a straight line. What I have found
is that if you plot percent dot area specifed in a Postscript file as
the input along the x-axis and then plot L* along the Y-axis it will be
very close to linear for a 150 dpi AM screen printing system that has a
20% to 25% dot gain. This is plotting the end to end response of a
printing system. Note that L* is linear with respect to visual
perception. The reflected energy measured from this same step wendge is
not linear.
Please note that the above result is not true for newsprint (it has a
higher dot gain) and it is not true for 10 micron stochastic on coated
paper( it also has a higher dot gain). The apparant gamma depends on
the paper, ink, and screening used. It makes no sense to say "Ink on
paper" has a gamma of 1.8". It depends on a lot a factors of the
printing system.
Ray Maxwell
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