Digital BW, The Print

--- In DigitalBlackandWhiteThePrint@yahoogroups.com, "Roy Harrington" 


> Very nice write up about inks and dithering an all.  A minor
> nitpick is that you show how 2 inks give more gray values.
> Quite true, but its even more dramatic than that -- the 2x2
> pattern can give 15 possible grays without overprint .
 
How do you figure?  I think you counted duplicates.  Say we call 
black "1" and gray "0.5".    I say the possible values are 0, 0.5,
1, 1.5, 2, 2.5, 3, 3.5, and 4.     Don't forget there are several 
different patterns that add up to 1.5 or 2.5. 

>                  One of the crucial issues if how much
> lighter the light ink is.  I think most light inks are quite a
> bit lighter than 50%.

That only helps a little - it eliminates the duplicates 
resulting from two 0.5's adding up to a 1, i.e., 1.5,  
2.5 and 3 in the prior example.   Say we called gray 0.3.
Then you get 0, 0.3, 1, 1.3, 1.6, 1.9, 2, 2.3, 2.6, 3, 3.3,
and 4.  The downside is that the new values are nonlinear.