Digital BW, The Print

--- In DigitalBlackandWhiteThePrint@yahoogroups.com, "Johnny Eades" 
<jeades1@s...> wrote:
> 
> Thank you Steve and Dijon for responding. Focus on the 128 to 147 
> (mifflr gray) difference between GG2.2 and GG1.8. In the info window, 
> when I place the dropper over middle gray, what should it read for my 
> system set up in GG1.8? It always reads 128 except for one downloaded 
> from Jon Cone's Piezography website. Dijon, how would you have worded 
> my question?
> 
> Still your friend in Photography,
> 
> Johnny

Johnny,

What you are seeing is the results of profile conversions based on the
working spaces you've selected in PS.   If you have a 21step in grayscale
internally the 50 step is always 127 or 128 = 50-K.   The "128" however is hidden
-- grayscale is always displayed in K which is  100-(internal/2.55). 
What you are looking at is the RGB values in the info pallette and they are
the conversion of grayscale to working RGB.    So if you have the RGB
working space set to Adobe RGB its a gamma 2.2 space.  Gray gamma 2.2
matches so you see R=G=B=128.   But if you have gray gamma 1.8 converted
to Adobe RGB the numbers are different i.e. R=G=B=145 is displayed but the
gray value really is 128 or K=50 underneath.

With PS its very hard to get away from all the color management things 
happening under the hood.  If you have PS CS you can set the info palette to
16 bit and see the extra bits -- the values range from 0 to 32768 instead
of 0 to 255 so you can calculate the midpoint which is 16384 = 50 step.
(If you take an 8bit 21step and convert the numbers are a little off.)

Roy