Digital BW, The Print

Alex:

Good, we are making progress.  Overall, what is your purpose/goal of 
doing these experiments?  Where are you going with this?  Are you 
trying to develop from scratch an inkset that will create smooth, 
full range grayscale prints using only the Epson driver?

"a_pettit_jr" <a_pettit_jr@y...> wrote:

> First, I just wished to see what the relative intensity values 
would be measured by creating C and M and Y boxes with a white 
background, converting to BW via Luminance layer extraction and then 
just measuring them via a histogram - all in software - never 
actually printing the image. 
> This shows that Magenta is 'darker' than cyan. 
> When I used PictureWindows the lightness values for the Luminance 
layer were
> W = 100 %
> Y = 88 %
> C = 70 %
> M = 41 %
> B = 0 %
> I Photoshop, I did a LAB convert and then discarded all but the L 
layer and obtained a histogram of 
> W = 100 %
> Y = 66 %
> C = 50 %
> M = 33 %
> B = 0 %

OK, I now understand what you did with Picture Windows and Photoshop 
above.

> 
> The for the 21 step test strip I printed, I just converted to RGB 
space ( PicWindows ) and then printed. This BW 'shading' is quite 
typical of what I have always found with the E 2000P in printing a 
neutral tone file.
> 
> I did the Color to BW converstion prior to viewing the histogram 
because I wished to observe what the computer interpreted as the 
relative intensity (density) levels - that is what is done to a color 
image for BW processing normally anyhow...
> 
> The only printer output for these tests was the 21step strip.
>

Ok, you printed a 24-bit grayscale image.  What inks in what 
positions did you use to print the 21-stepwedge?  What Epson dialog 
settings did you use (Color or Black, Color Correction On or Off, 
what printer profile, etc.)?  

NOTE: Without applying a partitioned curve to a 24-bit BW image or a 
lumped/non-partitioned curve to an 8-bit BW image all you are testing 
is how the native, uncontrolled Epson driver responds.  Of course it 
will yield strange results.
 
> 
> I measured all the ink densities via dilution using a graduated 
dropper and water. I diluted the black to about 1000:1 to make it 
fairly  transparent and then diluted the other inks to the same 
eyeball density - that is where I saw the faint yellow tint in the 
other inks relative to the diluted black.
>

Very interesting procedure.  How the inks on paper reflect light to 
the eye might be better quantified if you p

> 
> SO, it still appears that the Color > BW conversion using either 
PhotoShop or PictureWindows computes Magenta as a denser color than 
Cyan. This is why I have intended to occupy the Magenta positions 
with the darker Cyan labeled inks for the first attempt. AND, the 
Epson driver puts more magenta ink in the 65%-95% 21step strip areas 
and greater cyan in the 35%-65% areas when printing a BW file - thus 
it seems to me that the Magenta ink should be the darkest .... no ???
>

The actual *color* Magenta may be darker (less luminious) than Cyan, 
I have not done the experiment.  However, the current ink positions 
of FS, FS-E, & PiezoBW are a historical artifact based on the 
original positions chosen by the developers of the PiezoBW driver who 
totally bypassed the Epson driver.  In reality, the inks can be in 
any position (eg., either yellow or photomagenta position could hold 
the darkest ink) if the driver is written correctly.  When MIS 
developed the FS inkset they wanted folks to be able to use the FS 
inks with the PiezoBW driver.  Because many folks wanted to also use 
the MIS inks with Epson drivers, a series of partitioned and 
lumped/nonpartitioned curves were developed to control the Epson 
driver with the inks in the historical positions.

 
> This is the result of my very poor experience with the VM set and 
having so much posterization - that I why I plan to swap the Ms with 
Cs and give it a try ....  A workflow in BW space will never correct 
for 'misplaced' inks ...


Many folks are using the VM and FS families of ink with an Epson 
driver quite sucessfully and producing smooth, nonposterized prints 
with the currently available workflows.  The partitioned workflows 
have been especially written for the current ink densities and 
*color* positions.  There may be mislabeled bottles or incorrectly 
filled carts, but there are no 'misplaced' inks.

Jeff Randall 



> 
> Thanks,
> Alex
> 
> 
> 
> --- In DigitalBlackandWhiteThePrint@y..., "jrandall1149" 
<jrandall@c...> wrote:
> > "a_pettit_jr" <a_pettit_jr@y...> wrote:
> > 
> > > The first set of values was obtained from creating an image 
with CMY
> > > saturated color blocks, doing a Luminance extraction, and then
> > > measuring their histogram grey levels...  C = 30 %  M = 59 % 
> > > Y = 12 %
> > 
> > The C and M gray inks must have been mislabled (interchanged) 
because 
> > these relative values are incorrect. C>M>Y (0-100% grayscale 
values 
> > where 100% is black)
> > 
> > Let's define your workflow better.  
> > 
> > 1) The test above was done with the hex FS inkset for Cone driver 
> > (where C=PC and M=PM)?
> > 2) You created and printed a CMY color file (with no K block)?
> > 2a) What were your printer settings?  
> > 3) You then cropped and scanned these three blocks with a flat 
bed 
> > scanner? 
> > 4) Did you crop each block seperately or did you include all 
three 
> > blocks and some white space?
> > 4) What scanner, software, and settings (eg., wp, bp, autolevels, 
> > color correction, etc.) did you use?
> > 5) What photoediting program did you use?
> > 6) Why did you extract luminance, why not go directly to the 
> > histogram?
> > 
> > > 
> > > I just printed the 21-step grey scale by converting to RGB 
space and
> > > then to the Epson 2000P. 
> > 
> > 7) Which inkset?
> > 7a) What ink positions?
> > 8) Did you apply any curve (like the Woolf hex-inkset lumped (non-
> > partitioned) curve?  If you didn't, the subsequent results can be 
way 
> > off base. You must use, tweak, or develop a work flow including 
> > curves (either partitioned or lumped) for your inkset and 
printer. 
> > You have to tell the Epson driver how to lay down these inks 
because 
> > the . 
> > 9) What were your printer settings? 
> > 
> > >The grey range from 65% to 95% is quite
> > > magenta biased and the 35% to 65% has the cyan cast. The Epson 
> > driver
> > > thus seems to expect that the Magenta position will create a 
darker
> > > BW shading.
> > 
> > I do not understand how the FS or FS-E inksets can have any color 
> > cast.  I apologize because I may not understand your terminology.
> > > 
> > > I again measured the MIS FS inks and the differing results show 
the
> > > variability in my eyeball comparisions ..
> > > B 100%
> > > C 30%
> > > M 8%
> > > Y 4.4%
> > > PCe 10%
> > > PMe 2.5%
> > 
> > 9) What image did you measure--the 21-stepwedge?
> > 10) Any difference in scanning from above?
> > 11) I don't understand your numbers, but they do show that C is 
> > darker than M is darker than Y.  And that PCe is lighter than C 
and 
> > that PMe is lighter than M. These are the correct relative 
densities.
> > > 
> > > I intend to install the inkset with the Cyan and PCyan swapped 
with 
> > the
> > > Magenta and PMagenta. There is too much inconsistency between 
what I
> > > measure and what the Epson Driver does vs the labels on the MIS 
FS
> > > bottles to Not do so....
> > 
> > Put each gray ink in the position labeled on the bottle (after 
> > checking that the density ranges from dark to light C>M>Y).  Then 
> > apply a work flow designed for the Epson driver and your 
printer.  
> > I'd start out with the Woolf hexset curve. 
> > > 
> > > 
> > > 
> > > --- In DigitalBlackandWhiteThePrint@y..., "jrandall1149"
> > > <jrandall@c...> wrote:
> > > > Alex:  
> > > > 
> > > > For both the hex-FS and hex-FS-E inksets the Cyan position 
ink is 
> > > > dark gray, the Magenta position ink is middle gray and the 
Yellow 
> > > > position ink is light gray. This is not consistant with your 
> > first 
> > > > test. 
> > > > 
> > > > In the hex-FS, the PM position ink is the same as the M 
position
> > > ink 
> > > > and the PC position ink is the same as the C position ink.
> > > > 
> > > > In the hex-FS-E, the PM position ink is a dilution of the M
> > > position 
> > > > ink and is therefore lighter and the PC position ink is a 
dilution
> > > of 
> > > > the C position ink and is therefore lighter.  Your second 
test of
> > > the 
> > > > hex-FS-E inks are consistant with this.
> > > > 
> > > > Try a swab test using a q-tip and visually compare.
> > > > 
> > > > Jeff Randall
> > > >