[Tig] Question about 10bit log to 8bit lin

Jim Houston jdhouston at earthlink.net
Wed Aug 7 20:05:20 BST 2013


0.6 is the assumed capture gamma of a negative film stock
which can be plotted on a log log plot as a straight line with a
slope of 0.6.

Dividing the density value ( (  Refblack-Refwhite ) * 0.002 )
by the 'negative gamma' 0.6  converts to a reproduction density
with an assumed gamma of 1.0 which you can then
exponentiate 10^   to get transmission in linear light.
So proper conversion of density to linear light requires adjustment
based upon the capturing media 'gamma'.  It is better
to do this with the exact gamma if it is known, but the assumed
average in Cineon of 0.6 works well enough for most cases.


Jim Houston
Starwatcher Digital
Pasadena, CA


On Aug 7, 2013, at 2:02 AM, liao.zd at gmail.com wrote:
> 
> And why the "density per code value" is divided by the "slope of the straight line on a log-log plot for a sensitometric curve"?
> 0.002/0.6 = 1/300
> 




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