Digital BW, The Print

--- In DigitalBlackandWhiteThePrint@y..., David Dyer-Bennet <dd-
b@d...> wrote:

<snip>
So I've looked at the Brandon, Randall, and Woolfe curves (and
workflows) at MIS to consider a partitioned workflow.  
 
The big thing that bothers me about all of these is that I have no 
way to fix the curves for myself or generate curves for a new paper, 
or select the optimal media and paper settings, or anything.  I'd 
have to use them for packaged systems.  (And none of them have curves 
for Glacier Matte or Aspen).
<snip>

Since I don't have a densitometer this may be an essentially insoluble
problem. 
<snip>

Anybody have a method for end-users to produce their own quadtone 
separation curves? <snip> 

David:

I publish the RGB I/O values so folks CAN tweak the curves for them 
selves (it is a lot easier using Picture Windows, but that's another 
story).  I generated my 1160 partitioned curves using only a scanner 
as my densiomenter.  It can be done.  It's not rocket science.  It 
only take time, paper and ink.  

My basic procedure for generating partitioned curves is to scan a 21-
stepwedge in color with VueScan setting the WP and BP to clip the 0 
and 255 patches and autolevels color balance.  I then open the file 
using Picture Windows curves/histogram feature in the HSV colorspace 
and check the location of the other 19 "peaks" across the 0-255 range 
and iteratively adjust the partition curves to evenly space the 
peaks.  This is just manually building an inkset/printer/paper 
profile. 

Jeff Randall