Digital BW, The Print

Hi Carl,

>The Epson 4000 driver dither is already quite good 
>with just single channel BO so it might be a good 
>candidate for multiple Eboni channels.

I've been testing my 2200 with multiple Eboni ink channels as well as the
1800.  In general, the multiple channels can greatly reduce or virtually
eliminate microbanding, but it does not smooth out the grainy 2200 midtones.
So, the graininess you see with BO is probably what you'll get with multiple
Eboni channels.  The larger dots to print slightly more neutral, which I'd
say is an advantage.  However, the 1800 Eboni prints on non-brightened
Premier Art Smooth (Hot Press) 325 are definitely a tone I can live with --
just slightly warm.

The very light tones are actually better with a single channel firing.  I'm
getting close to "perfect" 1800 images (with a barely visible fine grain
structure) by having a single jet fire to 25%, another one start there,
another at 50%, and another at 75%.  

How many channels are optimum is still an open question.  From what I've
seen 3 may be a bit too little, and more than 4 may not result in any
visible improvement.  Whether the extra 1800 channels are useful is an open
question.  So far I'd say that as soon as Roy gets the new 260 and 1400
going, they'll make good candidates for this approach.  

Have you done a BO print with Epson PK?  I'm wondering how neutral it is.

I'm using QTR for this, with curves simply entered in the point lists.  The
channels are not partitioned, since they are all the same density.  The inks
never go into a negative slope.  Right now most curves are essentially
straight lines, with the caveat that I make the starting points of all but
the first one more gradual than a straight line would be.  The last curve,
which carries much or the black, has a highly increasing slope.  I'll
probably come up with a more or less overall slope and then figure out how
to make the system more simple and equalize ink usage somewhat.  Right now I
have not figured the areas under the curves.

I'll be sending this defective 1800 back soon, but, again, I think for those
interested in a pure carbon print that will not suffer from the inevitable
differential fade of the magenta & cyan color pigments, it tentatively looks
like a viable solution for up to 13 x 19.

Paul
www.PaulRoark.com