Jeff,
Are you sure that the Epson driver with the Woolf workflow mixes all
the inks equally? I would expect to see dots in the 0-20% range,
which I don't? I haven't examined with it with a lupe, but to the
naked eye I don't see any. Maybe it's just my old feable eyes! :-)
Would your method work equally as well with a CMYK setup. It seems
like it would and it might give even more control - especially over
the black?
I'll start with the Woolf lumped curve since that is what I'm
familiar with at the moment and have done a lot of tweaking, but
totally by eye. After that maybe the partitioned RGB or CMYK. I
would really like to be able to control the 100-80% better than I
can now. Al lthis is being done on a Epson 980.
Thanks again for your help,
Craig Spaulding
--- In DigitalBlackandWhiteThePrint@y..., "jrandall1149"
<jrandall@c...> wrote:
> 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
> > > grayscaleall 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).