Digital BW, The Print

What I'm trying to do is find a good way to see how smooth (or not) the
grayscale ramps are on the various inkjet workflows.  It is, perhaps, a way
to judge the extent to which the workflow can produce smooth, photographic
prints.

The procedure I tried here (and would like some feedback on) was to run a
Photoshop gradient at 50% opacity over and the opposite direction of the
21-step gray scale smooth ramp of the scanned test strips being compared.
The purpose of this procedure is to neutralize the ramp -- except for those
parts of the printed ramp that deviate from the Photoshop gradient ramp that
was used to make the test file in the fist place.  What should stand out, I
hypothesize, is the defects in the printing system/workflow.

To further accentuate the defects/deviations, I increased contrast 90% and
brightness 30%.

For comparison, I used one Piezo 1160 test strip (Piezo ink and driver ver.
5.1.3 on EAM with EAM profile) and one test strip printed with the 3000
using the VM-sepia ink with the neutral curve (a modified vm "warm" curve)
and, of course, the Epson driver.  This print was also on EAM.

Both test strips were then scanned at the same time.  (The scanner has a
defect that put 2 lines in the shadows of both test strips.  One is in the
100% patch and one in the 95% patch.  They are obvious in the image because
they are the same for each test strip.)

We are, of course, familiar with the dots that the 3000 has with the Epson
driver, and the dots do stand out.  So this comparison shouldn't even be
close. Right?

Take a look at the scanned image.  It is in the Files section, which is at:
http://groups.yahoo.com/group/DigitalBlackandWhiteThePrint/files/

Then go to > Inksets, reviews and techniques and see "Ramp-smoothness.jpg."

(The full URL is:
http://groups.yahoo.com/group/DigitalBlackandWhiteThePrint/files/Inksets%2C%
20reviews%20and%20techniques/Ramp-smoothness.jpg

But Yahoo mail wrecks the ability to click on wrapped URLs.)

Piezo wins the dot contest easily, but it has lots of vertical lines in it.
Overall, the contest is rather closer than one would expect.

The reason I originally started making Photoshop curves to print Piezo inks
with the Epson driver was to get smooth skies in some photos that Piezo was
putting lines in.  I suspect the vertical lines in this test are what was
causing the trouble with the Piezo outputs.  It would be interesting to see
how version 6 and the 7000 Piezo software does.

Of course, I don't expect to see perfection in any ramp, and I'm sure most
of the vm curves that I've done are even more defective than the one used
here (which is a new one just for the VM-sepia inkset to give a neutral
print).

I think this test is consistent with the comments we've heard lately
comparing digital and darkroom prints.  I think we still have a ways to go.

Paul
http://www.PaulRoark.com

Lines in the sky?  Not with my 7000 / Piezo ProB&W.

--
Quentin

--- In DigitalBlackandWhiteThePrint@y..., "Paul Roark" 
<paul.roark@v...> wrote:
> What I'm trying to do is find a good way to see how smooth (or not) 
the
> grayscale ramps are on the various inkjet workflows.  It is, 
perhaps, a way
> to judge the extent to which the workflow can produce smooth, 
photographic
> prints.
> 
> The procedure I tried here (and would like some feedback on) was to 
run a
> Photoshop gradient at 50% opacity over and the opposite direction 
of the
> 21-step gray scale smooth ramp of the scanned test strips being 
compared.
> The purpose of this procedure is to neutralize the ramp -- except 
for those
> parts of the printed ramp that deviate from the Photoshop gradient 
ramp that
> was used to make the test file in the fist place.  What should 
stand out, I
> hypothesize, is the defects in the printing system/workflow.
> 
> To further accentuate the defects/deviations, I increased contrast 
90% and
> brightness 30%.
> 
> For comparison, I used one Piezo 1160 test strip (Piezo ink and 
driver ver.
> 5.1.3 on EAM with EAM profile) and one test strip printed with the 
3000
> using the VM-sepia ink with the neutral curve (a modified vm "warm" 
curve)
> and, of course, the Epson driver.  This print was also on EAM.
> 
> Both test strips were then scanned at the same time.  (The scanner 
has a
> defect that put 2 lines in the shadows of both test strips.  One is 
in the
> 100% patch and one in the 95% patch.  They are obvious in the image 
because
> they are the same for each test strip.)
> 
> We are, of course, familiar with the dots that the 3000 has with 
the Epson
> driver, and the dots do stand out.  So this comparison shouldn't 
even be
> close. Right?
> 
> Take a look at the scanned image.  It is in the Files section, 
which is at:
> http://groups.yahoo.com/group/DigitalBlackandWhiteThePrint/files/
> 
> Then go to > Inksets, reviews and techniques and see "Ramp-
smoothness.jpg."
> 
> (The full URL is:
> 
http://groups.yahoo.com/group/DigitalBlackandWhiteThePrint/files/Inkse
ts%2C%
> 20reviews%20and%20techniques/Ramp-smoothness.jpg
> 
> But Yahoo mail wrecks the ability to click on wrapped URLs.)
> 
> Piezo wins the dot contest easily, but it has lots of vertical 
lines in it.
> Overall, the contest is rather closer than one would expect.
> 
> The reason I originally started making Photoshop curves to print 
Piezo inks
> with the Epson driver was to get smooth skies in some photos that 
Piezo was
> putting lines in.  I suspect the vertical lines in this test are 
what was
> causing the trouble with the Piezo outputs.  It would be 
interesting to see
> how version 6 and the 7000 Piezo software does.
> 
> Of course, I don't expect to see perfection in any ramp, and I'm 
sure most
> of the vm curves that I've done are even more defective than the 
one used
> here (which is a new one just for the VM-sepia inkset to give a 
neutral
> print).
> 
> I think this test is consistent with the comments we've heard lately
> comparing digital and darkroom prints.  I think we still have a 
ways to go.

> 
> Paul
> http://www.PaulRoark.com

on 3/27/02 10:28 AM, Paul Roark wrote:

> The procedure I tried here (and would like some feedback on) was to run a
> Photoshop gradient at 50% opacity over and the opposite direction of the
> 21-step gray scale smooth ramp of the scanned test strips being compared.
> The purpose of this procedure is to neutralize the ramp -- except for those
> parts of the printed ramp that deviate from the Photoshop gradient ramp that
> was used to make the test file in the fist place.  What should stand out, I
> hypothesize, is the defects in the printing system/workflow.
> 
> To further accentuate the defects/deviations, I increased contrast 90% and
> brightness 30%.

Paul

Thanks for sharing your tests.

Could you run through your reasoning/methodology one more time? I thought
the smooth grayscale/step-wedge was already a good representation of a
challenging print. I'm not sure I follow why you took the extra steps you
did.

That's not to say it wasn't a good idea, just that I don't get it yet.

Thanks,
Todd

Todd,

>Could you run through your reasoning/methodology one more time? I thought
>the smooth grayscale/step-wedge was already a good representation of a
>challenging print. I'm not sure I follow why you took the extra steps you
>did.

I think that subtle problems in prints of the 21-step test file ramp may not
be obvious in that test, but do show up in some prints.  Not infrequently, I
hear of trouble with subtle gradations where the test print from the person
looks OK.  I think we also heard the conclusion from a forum member that in
comparison with wet prints, the inkjet prints don't do well with low
contrast subjects.

So, I wanted to find a test that would show more subtle deviations in the
ramp.  The basic idea was to neutralize the ramp itself with the gradient
going the other direction, and then raise the contrast to show the
deviations more clearly.

I think the procedure works.  It might be that where someone says a print
looks odd at a certain area, taking a test print from the same printer and
workflow, this procedure would be able to identify the problem where just
looking at the ramp it is not clear there is a problem.

Anyway, I thought it was an interesting exercise.  My Piezo ramp is sure far
from the perfection that some claim for that workflow.

Paul
http://www.PaulRoark.com

Paul,

Yes, on further reflection I see the merit in what you did. For one thing
you increased the likelihood of localized artifacts to show up by putting
them in two places rather than one, and you first decreased the contrast of
the target which allowed you to then increase it to heighten the flaws.
Makes sense.

Thanks.
Todd

> Todd,
> 
>> Could you run through your reasoning/methodology one more time? I thought
>> the smooth grayscale/step-wedge was already a good representation of a
>> challenging print. I'm not sure I follow why you took the extra steps you
>> did.
> 
> I think that subtle problems in prints of the 21-step test file ramp may not
> be obvious in that test, but do show up in some prints.  Not infrequently, I
> hear of trouble with subtle gradations where the test print from the person
> looks OK.  I think we also heard the conclusion from a forum member that in
> comparison with wet prints, the inkjet prints don't do well with low
> contrast subjects.
> 
> So, I wanted to find a test that would show more subtle deviations in the
> ramp.  The basic idea was to neutralize the ramp itself with the gradient
> going the other direction, and then raise the contrast to show the
> deviations more clearly.
> 
> I think the procedure works.  It might be that where someone says a print
> looks odd at a certain area, taking a test print from the same printer and
> workflow, this procedure would be able to identify the problem where just
> looking at the ramp it is not clear there is a problem.
> 
> Anyway, I thought it was an interesting exercise.  My Piezo ramp is sure far
> from the perfection that some claim for that workflow.
> 
> Paul
> http://www.PaulRoark.com
> 
> 
> 
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