QTR-Quadtone RIP

Hello,

I am new to B&W printing using a B&W ink set. I am also new to QTR. So I have a number of questions concerning profiling and curve creation. I think I have gotten my head around basic colour profiling and I have color profiled my colour printers and papers using a SpyderPRINT spectrometer with success.

This is my setup ( just to get technicalities out of the way)

A Mac running 10.8. I work and normally print from Apple Aperture, but I have Photoshop CS6 at my disposal
My B&W printer is a Epson Photo R265 (known as a R260 in the US). This is a Claria 6 ink printer
I use UT-3D as the B&W inkset in this printer, based on sample printouts I had seen. I generally like the look and feel of this ink set. I also like neutral toned prints.
My favourite paper is Ilford Gold Fibre Silk (for glossy) and Hahnemühle PhotoRag for matte paper.
I know howto, print raw profile images, like the 21-step wedge, bypassing colour management.
So far I used this printer using the standard Epson printer driver to print by B&W photos, essentially letting the printer driver do the colour management. The results are mixed, although sometimes this results in stunning printouts.

So I have tried to create ICC curves using the QTR create ICC profile script, but fail miserably, because my blacks seem to saturate off at about the 85% mark, and I have the impression, the printer driver puts down too much ink, which the paper cannot absorb.

Is there a way to reduce the amount of ink output from inside the Epson printer?

If reducing the ink in the Epson driver is not possible,I assume I have to go via the route of creating a curve and use the QTR printer driver, where reducing the ink is possible. Unfortunately, nobody seems to have created curves for this type of printer (or a similar one like the R380) and the UT 3D ink set, and the process of creating a curve seems overly complicated. In addition, most description of curve creation either assumes a colour ink set or a BO approach. 

What would be the approach to create a curve using this ink set. Has anyone a step by step outline or tutorial specifically for UT 3D (or similar ink sets?)

What should I try next?

Finally when I set up the QTR driver I had the choice between a QuadR260 and a QuadR260-MIS. What is the difference?

Thanks in advance and sorry for the verbose and lengthy mail

Andrew



Sent from my iPad

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Andrew Maier <andrew@...> wrote:

> **
>
>
> ... questions concerning profiling and curve creation....
>
using a SpyderPRINT spectrometer with success.
>
> ... Mac ... a Epson Photo R265 (known as a R260 in the US)... UT-3D as the
> B&W inkset in this printer,... like neutral toned prints...  My favourite
> paper is Ilford Gold Fibre Silk (for glossy) and Hahnemühle PhotoRag for
> matte paper.
> ...
>
For general information about the inkset, see
http://www.paulroark.com/BW-Info/UT-3D_Readme.pdf.

I have tried to create ICC curves using the QTR create ICC profile script,
>
Use Create ICC-RGB.  It allows you to drop a Photoshop image adjustement
curve into the ICC as well as the linearization data.  See
http://www.paulroark.com/BW-Info/Embedding_Photoshop_Curves_in_ICCs.pdf

... my blacks seem to saturate off at about the 85% mark, ...
>
You can control that with the PS curve you embed in the ICC or with a
profile you make for QTR.  If the 21-step with no curve hit its dmax at
85%, then have a curve that ends at 85% on the black end of the curve.
 Then look at where the inks are and how the R, G and B curves will affect
the C, M and Y inks.  That will give you the control you need.  Start with
the 50% patch and points on the curves at that input level.  When you get
the 50% tone right, go to the 25% and 75% points.  It's a iterative process
(aka trial and error, but you'll probably get the hang of it after a few
moves).

(Because I'm Windows, I'm not going to get into QTR profiling on a Mac, and
the color management issues may be different.)

Paul
www.PaulRoark.com


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Hi Paul,

Thanks a lot for your answer, I think I am getting closer, but I still have
some questions. In particular concerning the RGB channels of the curve.
(See below)

On 2 August 2013 05:09, Paul Roark <roark.paul@...> wrote:

> **
>
> For general information about the inkset, see
> http://www.paulroark.com/BW-Info/UT-3D_Readme.pdf.
>
> Thanks, I had already read this already

>
> I have tried to create ICC curves using the QTR create ICC profile script,
> >
> Use Create ICC-RGB. It allows you to drop a Photoshop image adjustement
> curve into the ICC as well as the linearization data. See
> http://www.paulroark.com/BW-Info/Embedding_Photoshop_Curves_in_ICCs.pdf
>
>
Yes I meant to say the ICC-RGB script.

One question, embedding the Photoshop curve, will I still be able to use
the ICC profile to print from any software, or will this become a Photoshop
only ICC?


> ... my blacks seem to saturate off at about the 85% mark, ...
> >
> You can control that with the PS curve you embed in the ICC or with a
> profile you make for QTR. If the 21-step with no curve hit its dmax at
> 85%, then have a curve that ends at 85% on the black end of the curve.
> Then look at where the inks are and how the R, G and B curves will affect
> the C, M and Y inks. That will give you the control you need. Start with
> the 50% patch and points on the curves at that input level. When you get
> the 50% tone right, go to the 25% and 75% points. It's a iterative process
> (aka trial and error, but you'll probably get the hang of it after a few
> moves).
>
>
So the process would be the following.

1. Create a curve where the black endpoints end at 85%, that is the curve
is still linear (less steep curve), but black ends at the 85% level

2. Reprint the 21-Step wedge using Photoshop, thereby applying the curve to
reduce, the ink output at the high end.

3. Remeasure with the spectrometer and use the output from the spectrometer
+ the applied curve to create a ICC?

This will cause a problem, as now with CS6, Photoshop (at least on the Mac)
will not allow to print anything unmanaged. I will have to assign a colour
profile. This defeats the process. Since Adobe is aware that you will want
to print targets unmanaged, they have created a small app called "Adobe
Printer Utility", which takes a tiff and prints it unmanged. But this app
will not apply the curve. The only thing which might work is to take the
21-Step, apply the curve and save a copy thereby preventing it from
applying a profile. Then use the utility to print out the "new" target and
redo the measurement.


Once I have the black sorted out, I would have to sort out the RGB
channels. What I have not quite understood,  what do I do with the colour
channels? Do I measure the a* b* values and try to minimize them, or what
is the aim here? So I would start to would take the 50% patch, measure it's
Lab values, before and after applying the curve and then try to move the
RGB part of the curve to make them as close as they were before, or as
close to zero, or as close as possible to the a*, b*  values white patch?




> (Because I'm Windows, I'm not going to get into QTR profiling on a Mac, and
> the color management issues may be different.)
>
Paul
> www.PaulRoark.com
>
>
>

Thanks again!

Andrew

-- 
Andrew Maier PhD, PMP
tel: +41 79 34 19 492
email: andrew@...
linkedin: http://ch.linkedin.com/in/andrewmaier


[Non-text portions of this message have been removed]

Andrew Maier <andrew@...> wrote:

> **
>
>
> ...
>
>
> > Create ICC-RGB ... allows you to drop a Photoshop image adjustement
> > curve into the ICC as well as the linearization data. See
> > http://www.paulroark.com/BW-Info/Embedding_Photoshop_Curves_in_ICCs.pdf
> >
> >
>
> One question, embedding the Photoshop curve, will I still be able to use
> the ICC profile to print from any software, or will this become a Photoshop
> only ICC?
>

I believe the ICC is usable with other applications.  That is one reason to
use Create ICC-RGB.  It's compatible with most applications as far as I
know.



>
>
> > ... my blacks seem to saturate off at about the 85% mark, ...
> > >
> > You can control that with the PS curve you embed in the ICC or with a
> > profile you make for QTR. If the 21-step with no curve hit its dmax at
> > 85%, then have a curve that ends at 85% on the black end of the curve.
> > Then look at where the inks are and how the R, G and B curves will affect
> > the C, M and Y inks. That will give you the control you need. Start with
> > the 50% patch and points on the curves at that input level. When you get
> > the 50% tone right, go to the 25% and 75% points. It's a iterative
> process
> > (aka trial and error, but you'll probably get the hang of it after a few
> > moves).
> >
> >
> So the process would be the following.
>
> 1. Create a curve where the black endpoints end at 85%, that is the curve
> is still linear (less steep curve), but black ends at the 85% level
>
> 2. Reprint the 21-Step wedge using Photoshop, thereby applying the curve to
> reduce, the ink output at the high end.
>
> 3. Remeasure with the spectrometer and use the output from the spectrometer
> + the applied curve to create a ICC?
>

Yes, in effect.  The linearization is automatically done by Create ICC-RGB,
but the print tone control is something you do by altering the points on
the curve -- the same on that ends at 85%.  Just print 21-step test strips
with the PS curves until you get the print tones right (and Lab L curve
reasonable).  Then use that as the final PS curve and use the Lab L from
that test strip for the linearization.



>
> This will cause a problem, as now with CS6, Photoshop (at least on the Mac)
> will not allow to print anything unmanaged. I will have to assign a colour
> profile.
>

The PS working space should be Adobe RGB (1998).  The print driver is set
to ICM/No Color Adjustment, PS is set to PS controls colors, and the Adobe
RGB (1998) profile is put in the profile box.  That, at least, is what
works with CS5 and Windows.  If the working space and profile are the same,
I believe the file's values will be un-altered.  (Once the ICC is done, it
works with grayscale files.)


> ... what do I do with the colour
> channels? Do I measure the a* b* values and try to minimize them, or what
> is the aim here?
>

You'll have to determine what look you want.  For a neutral looking print,
keeping the Lab A about the same as the paper base usually works.  A slight
rise -- one unit -- will give you more of a "selenium" look.  I would try
to keep the Lab A values from dipping too much at least through the
midtones.

For a neutral print Lab B also would be flat with a paper that is not
filled with OBA's.  If the paper base is cold, a straight line from the
paper base to the deep shadow values will look neutral/cool.

Obviously for warm you'll want an elevated Lab B, and a Lab A rise will
give more of a red-brown warmth than the yellow Lab B.



> So I would start to would take the 50% patch, measure it's
> Lab values, before and after applying the curve
>

Once you print with the curve ending at 85% (where the dmax will hopefully
be at the 100% patch then), you might want to measure the entire 21-step.

I like to open the file in Excel and graph it (insert line chart).  Graph
the Lab L in one "chart" (Excel terminology) and Lab A and B in a second
chart.  In the Lab A and B chart, I like the vertical scale to be a total
range of 10, with one unit steps.  Excel will default to a range that is
just enough to cover the measured values.  You'll drive yourself crazy if
you try to control the tones down to small percentages of one unit.

By the way, for the curve that stops at 85%, use the R, G and B curves
individually.  It's those individual curves that you'll be manipulating.

When you have the graph of the tones of the straight line 0 - 85% curve,
you can move more points than just the 50%, but moving that one will move
the others also.  So, it's not a bad place to start.

One thing to consider is that if the tones are just right at some point(s)
of the curve, nail those down by putting a point there, so that it will not
be altered when you move other points.

Hope this helps.

Paul
www.PaulRoark.com


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