Digital BW, The Print

Actually if you go work this out, a dynamic range from L*=16 (a change from
below but a figure nearer to dMax on matte paper) to L*=96 with linear steps
in L* in between has a gamma of approximately 2.0. The curve:

Luminance/print reflectance (ie XYZ_Y) = 0.882 x NPV^2.0 + 0.021

is a very good fit.

(NPV = normalized pixel value, ie it can range from 0 to 1 regardless of bit
depth; 0.021 is dMax or black level measured in XYZ_Y, ie a density of 1.68;
the 0.882 is brightness...at NPV=1 we get print reflectance=0.9 or L*=96, ie
paper white) 

So working towards a target gamma of 1.8 would result in a greyscale with
even LESS contrast than a conventional unadjusted QTR/Epson print on matte
paper....


> From: Steve Kale <stevekale@...>

> 
> This is very helpful and I think we are talking apples to apples!  I don't
> know what gamma is implicit in a linearized L* greyscale from, say, L*=15ish
> to L*=96ish but I suspect it is a lot less than 1.8 (and especially 2.2).
> Someone smarter than me can figure that one out.  So tackling the issue of
> greyscale gamma, as you are doing, is, I think, something that needs to be
> addressed.