Digital BW, The Print

Jeff,

I have several questions re your transfer curves technique:

1) Can the black and white points be set in Photoshop instead of the 
scanner after the step-edge has been scanned? I work with a digital 
camera and my scanner is marginal and I don't think the black and 
white points can be set in the software.

2) Is this a technique for making a transfer curve or a curve that 
is to be applied in an adjustment layer? Once the curve is made, can 
it be applied either place?

3) Is there a good method for going about modifying an existing 
curve (like the Woolf)? Do you click on the appropriate step in the 
step-wedge to find out where it is on the curve that step is, then 
use the up/down arrow or change the numbers in the dialog box? If 
so, is there a rhyme or reason for how much to change it to equally 
space out the peaks, or, is it all trial and error. Or, do you just 
focus on changing the general shape of the curve to space out the 
peaks?

Thanks for any help!

Craig Spaulding

--- In DigitalBlackandWhiteThePrint@y..., "jrandall1149" 
<jrandall@c...> wrote:
> David:
> 
> Take any of the 21-step wedge test files available and crop to 
just 
> the steps (eliminate any continious ramp, surrounding background 
> space, and seperator lines in the step area) and then use the 
> histogram function of your image editing program.  You will see 
the 
> peaks to be equally spaced between 0-255 or 0-100%.  This 
indicates 
> to me that if you print out the step wedge and then scan it and 
check 
> the image as above, you should end up with evenly spaced peaks
> (assuming as you said a good scanner).
> 
> This is the logic I used when I created the RGB partitioned curves 
> for the 1160 (see MIS web site or Files here). During scanning I 
set 
> the blackest black of step wedge test print to 100% (or 0 value) 
and 
> the whitest white (=color of paper) to 0% (255)--that is I 
expanded 
> the maximum range on my paper to the "theoretical" 0-100 range. I 
> then tweaked to curves to equally space the other 19 peaks.
>  
> I have also used this approach to tweak Woolf's lumped (non-
> partitioned) single curve work flow.  I haven't tried Jerry 
Nivin's 
> workflow, but I suspect it is the same or similar.  
> 
> So my suggestion (don't know if it is technically correct or not, 
but 
> it seems to work for me) is to shoot for equally spaced peaks.
> 
> Good Luck.
> 
> Jeff Randall
> 
> 
> --- In DigitalBlackandWhiteThePrint@y..., David Dyer-Bennet <dd-
> b@d...> wrote:
> <snip> 
> > I noticed recently somebody pointing out that the histogram from 
a
> > step wedge of equal steps should be a nice comb of equally-spaced
> > spikes.