Digital BW, The Print

Craig:

The outlined method I posted is for creating a partitioned RGB curve 
set (one that controls each of the three shade of gray seperately).  
The Woolf workflow lumps all three gray inks into one, yielding a two 
ink system (gray and black). Therefore no need to do Step 1.  Step 4 
would use the Brightness Curve function in HSV colorspace instead of 
the Color Curve function.  ETC.

Another point about the Woolf workflow is that the color positions of 
the gray inks don't matter, because they are all mixed in approximate 
equal proportions by the Epson driver.  So this workflow (approach 
not the exact curve) can work for MIS original, or MIS FS, or any 
inkset with different ink positions or ink densities.

I suggest you read the both Woolf's and my workflow documents for 
additional details.

Jeff Randall  

--- In DigitalBlackandWhiteThePrint@y..., "craig_spaulding" 
<craig_spaulding@y...> wrote:
> Jeff,
> 
> Wow, thanks for the details. This will keep me going for a while...
> 
> Craig Spaulding
> 
> --- In DigitalBlackandWhiteThePrint@y..., "jrandall1149" 
> <jrandall@c...> wrote:
> > --- In DigitalBlackandWhiteThePrint@y..., "craig_spaulding" 
> > <craig_spaulding@y...> wrote:
> > > 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.
> > 
> > I've had better luck setting the b/w points during scanning than 
> > setting in my image editing software (your results may vary).  I 
> use 
> > VueScan as my scanning software and have found the histogram 
> feature 
> > to be very good. (www.hamrick.com). I use Picture Windows as my 
> image 
> > editing software because I think its curves/histogram feature is 
> the 
> > best of any editing package (I also use it for a lot more 
reasons, 
> > but that's another post) (www.dl-c.com). I also have and 
> occassionly 
> > use PhotoShop 6.0 
> > > 
> > > 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?
> > 
> > Transfer curve and adjustment layer curves are essentially the 
> same.  
> > They both map an input value (in what ever units) to an output 
> > value.  Because they use different units they are not directly 
> > interchangeable, but if you do the math you can create curves the 
> do 
> > the same thing in both worlds.
> > > 
> > > 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?
> > >
> > Here is an approach that I used to create my RGB Partitioned 
> Workflow 
> > for the 1160 and MIS FS inkset (and modify the Woolf lumped 
> > workflow).  It works for me (your milage may vary)  It is not a 
> > complete cookbook and every nuance is not spelled out.  
> > 
> > 1)  Print a quad purge image and scan using the procedure 
outlined 
> in 
> > step #3 to determine the approximate reflective values (I use the 
> 0-
> > 100% scale) of each pure ink on the paper.   Crop the image to 
> > produce approximately equal areas of the 4 inks and white space.  
> The 
> > ink values determine the maximum "density" that can be
> > achieved by 
> > each ink alone and serve as a guide to when the next darker shade 
> > must be started. 
> > 2)  Apply a starter RGB partitioned curve set to a 21-step wedge 
> test 
> > image and then print.
> > [Note:  I use the step wedge posted in the Files section of the 
> Yahoo 
> > Piezography3000 Group.  The file is piezmultisteps.psd.  It has 
> > excellent low (95-100%), medium (45-55%), and high (0-5%) 
> brightness 
> > test areas to allow you to visually  evaluate and set these 
> benchmark 
> > values. I initially used Paul Roark's curves he developed for the 
> > Piezography BW inkset and the Epson driver.]
> > 3)  I scan the print with my HP-5370 scanner using VueScan.  VS 
> > settings are: 
> > * Crop = tightly set to only scan the narrow 21 step portion of 
> the 
> > test image. Don't include any of the grayscale ramp or the 
portion 
> of 
> > the 21 stepwedge with the light or dark separator lines.  My goal 
> is 
> > to have 21 separate and narrow histogram peaks with little noise 
> in 
> > between.   
> > * Color balance = auto levels. I use auto levels because it sets 
> each 
> > RGB curve to the b/w points — neutral doesn't and white balance 
> > doesn't do this well.
> > [Note:  I don't care about the "color" of my
> > grayscale—all I'm 
> > interested in is the overall/combined brightness.]
> > * B/W points set to clip the 0% (255) and 100% (0) gray value 
> steps 
> > to expand the range to the maximum.  That is, set the 0% gray 
> value 
> > to the whiteness of my paper and the 100% gray value to the 
> blackest 
> > black I can print with the inkset. 
> > * Scanning resolution = 150 dpi. 
> > * Number of passes = 4.  This reduces noise and increases peak 
> > separation, especially in the dark end.  The exact pixel 
alignment 
> is 
> > not an issue with a stepwedge print.
> > * File color space = AdobeRGB
> > * Grain reduction = heavy.  This also seems to increase peak 
> > separation in the dark end.
> > * Tiff file type = 24-bit RGB
> > 4) I open the Tiff file in Picture Windows and apply the 
> Color|Curves 
> > function which combines a curve and histogram view of the pixels. 
> > [Note:  The PW Color Curve and grayscale Brightness Curve 
> functions 
> > can both display the image value, lightness, or brightness of the 
> > image in the HSV, HSL or RGB color spaces, respectively.  I use 
> the 
> > HSV color space because it does a good job of separating the 
image 
> > brightness component from the color components which I don't care 
> > about.  Image brightness in the RGB space is a weighted sum of 
> each 
> > RGB color and overall not as useful.]
> > 5)  I note on a worksheet whether each of the remaining 19 peaks 
> > needs to be moved lighter or darker and a relative amount.
> > 6)  I then load and apply the RGB partitioned curve used to 
create 
> > the tight crop of the 21 step wedge to my test image and adjust 
> each 
> > individual RGB curve (red=dark, green=medium, & blue=light gray), 
> as 
> > determined in Step #5. 
> > 7) I then save the new RGB partitioned curve under a different 
> name.
> > [Note: When I get close to where I want the peaks to be, I open 
> the 
> > Picture Windows RGB partitioned curve file (filename.cc) with a 
> text 
> > editor and manually change the values (which are stored as 0-255 
> > values) ]
> > 8)  I then print the test image.  
> > 9)  Iterate until you are satisfied (or run out of paper or ink).