Digital BW, The Print

James,

>I have been experimenting with the MIS UT7 inkset on a SP2200.

>... the UT7 inkset only provides 3 Black inks 
>while having 3 toners and a "custom light black"

The black/gray inks in the UT7 are the black, light black, cyan, and light
cyan.

In addition, the cool toners in both the UT7 and UT2 inksets have a lot of
carbon in them.  They are about the same densities as the dark and light
pure carbon inks.  It's a different approach to "toning" than in the
original VM and UT1 inksets.  The cool inks contribute significantly to the
overall density of the image.  This makes for better glossy printing, where
the light inks flood the paper and cause spots.

>Are there any visible dis-advantages to having only 3 black densities? 
>It seems like this could be less desirable in theory than the 4 black 
>densities of the UT2 inkset.

The UT7 inkset is close to the UT2 in basic approach and design, with the
addition, of course, of a light black.  So, there are actually more gray
inks in the UT7.  Also, with the separate carts, one can put an extra light
gray in the yellow spot of the UT7.

Compared to the UT1 and FS inksets, what the UT2 and UT7 lack is a very
light gray (like the old FS Y ink, a density that was designed to allow the
old 3000 to print smoothly).  This is why the UT2 and UT7 inksets should not
be used on older printers.

>Why would one use the "custom light black"?

The light gray ink is mostly used by the driver when R=G=B.  It is there
mostly to fight metamerism in the color inksets when the shadow tones are
neutral and would show it the worst.  In the UT7 inkset, the LK ink is used
mostly where grayscale files are printed with the sliders, and the sliders
are left in the neutral positions.  The target tone here is slightly warm.
However, when the standard LK kicked in, it caused a warm cross-over in the
shadows.  Then, when the Eboni kicked in lower in the shadows the hue
shifted back to only slightly warm, Eboni being much more neutral than the
OEM Epson Matte Black.  So, the UT7 LK tone was matched to the 50%, slightly
warm hue of the "EZ" (grayscale, no curves, sliders at 0) default printing
mode tone.  

>Why would one choose the UT7 inkset over the UT2 inkset for QTR?

The only ink that is common between the two is the dark gray, and it is in a
different position.  The differences are needed to allow each printer to hit
the target densities and tones (hues) in the "EZ" mode -- and they are very
different printers.  The two drivers' assumptions about the ink
characteristics vary because of the differences between the Epson dyes and
pigments.  The UT2 and UT7 inksets, however, basically use the same
approach.

I don't know how all this would relate to finding the optimum mix for QTR.

Paul
www.PaulRoark.com