Digital BW, The Print

ie with say the "M" and "m" positions 
> containing ink of an identical tone or density??? If this is what he 
> means is that true of all ink sets? Are hex tones really quads in 
> disguise???

 Damian,

in a word.... yes!  It all started back in the days of the old piezo plug in and 
piezo pro, then the approach was transferred over to ImagePrint. The old 
piezo inks and all current Piezotone inksets, as well as those of the MIS inks 
that claim to be compatible with the piezo software, use the exact same ink  
between Magenta and Photo Magenta and between Cyan and Photo Cyan. 

You could interpret this as missing out on the benefits of a true hex tone set - 
or, if you look closely, realize that the problem is not so much with using 6 vs 4 
shades of gray:  3 grays and a black will give you a fine grayscale, especially 
with newer printers like the 1280 and 2200 (assuming UT inks).  Most people 
are happy with the old 1160 and its quad scale. 

The reason for using the extra 2 inks to better advantage is twofold:

(a) you can use them as "toners" to cool or warm the overall print color
or
(b) you can use them with careful 6-color profiling to reduce the appearance 
of dots in older machines that tend to put down a bigger "device dot" . 

Both of these options are not possible with older software like the piezo 
plug-in, or ImagePrint. They are designed to produce a  4-ink scale. In fact, IP 
has an internal function of randomly using one or the other of the pairs (C/PC 
and M/PM) in an attempt to even out their use. But if one of your heads has a 
clog and the other doesn't , you'll go mad trying to chase it down ! 
Newer softwar like IJC addresses both issues, as would any 6- or 7-color true 
CcMmYK RIP.

The other problem with the current 4-ink or "fake 6-ink" sets, is that the density 
differences between inks is less than ideal. The Cyan position is very close to 
black, for example. Or, in the case of the 2200, 2 grays and a black might  be 
enough because the dots are so fine. Eventually we should get to a place 
where new inksets will be available with  better distribution of densities from 
lightest gray to black.


Antonis