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Digital BW, The Print

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Baffled by 3MK linearization with QTR

2008-09-13 by Roger

Good afternoon,

I am trying the 3MK QTR workflow with my R1800. I am not having luck
getting a grayscale ramp similar to UTR2 in a R220.  In general it has
far too open shadows and looks very flat.  I want a *reasonable match*
between the two printers (I don't expect perfection) as I want to be
able to print 4x6 on the R220 and 11x14s on the R1800 without having
to change the file in Photoshop.

Here are the steps that I've taken:

I have put Eboni carts in almost every spot and have determined that
PK, MK and Y give the smoothest (but still not exactly smooth)
results.  I don't really care that much about absolute smoothness on
large prints anyway- the UTR2 is visually dotless up to 8.5x11.

For the past few years I have been using the UTR2 inkset with my R220
using the Epson driver and QTR to create ICCs using PrintFixPro to
generate the measurements.  I use Paul's 21 step grayscale wedge.

I am attempting to create my own curve for the R1800 3MK for my
favorite paper, Innova SW 315.  I copied one of the other 3MK curves,
changed glop to yellow and deleted the linearization data.

This curve is here:
http://www.jingai.com/phototests/3MK-PKYMK-notlinear-InnovaSW315.qidf

Using QTR I printed a 21 step grayscale wedge on Innova 315.  I waited
a few minutes and measured it with PrintfixPro/SpyderPrint3.

I then pasted the density column into the linearization tab in the curve.
That gave me this result:
http://www.jingai.com/phototests/3MK-PKYMK-InnovaSW315.qidf

Visually the files I printed using this curve don't look right.  They
look very flat with far too much shadow detail.  Because the shadows
are so light it looks like there is a poor Dmax- true blacks actually
measure 1.65 so actual dmax is fine.  It's step 17-20 or so that are
way too light.

I then printed a 21 step grayscale wedge on the same piece of paper
using my R220 with UTR2, a QTR-generated ICC file using perceptual
with BPC on.  Driver settings where Gamma 2.2, Epson Standard and
paper type UPGPP and Best Photo- all standard per Paul's
recommendations.  I printed a second one using BPC off.

I saved all the measurements to an excel file and created a chart to
visualize them.  Please see that here:
http://www.jingai.com/phototests/innova%203mk%20linearized%20vs%20not.xls

Here's the odd thing- when you look at the line graph you see that the
non-linearized R1800 3MK is actually much closer to the linearized
R220 than the linearized R1800 curve!  It's still a bit too light in
the dark shadows for my taste, but at least is in the ballpark.  

Does anyone have an idea how to better match these printers or how to
get QTR to give me less shadow detail with the R1800?

Am I doing something else wrong with the curve creation?

(Built in profiles for Premier Art BW on that paper, and PhotoRag on
Photorag also look far too light to me)

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