Digital BW, The Print

On Monday, March 17, 2003, at 02:48  PM, Robert Morrison wrote:

Thanks for your comments Robert.
> I'm not sure that this approach...using CMYK controls...will 
> ultimately work
> for the BW printing with the ultrachrome printers...you need single 
> channel
> control...it may be less critical with a VM like set of inks.  The 
> problem
> is that when you alter the K you are leaving it up to gimp print to 
> decide
> how to make this from the black and light black.
You are right, I think that this is really a problem trying to control 
the two blacks
(and probably the C and M inks as well) through one channel.
I did notice that switching to 4 color standard mode turned off all of 
the light inks
but resulted in very coarse looking prints.
>   This give you no way to
> optimize dmax...which requires careful control of these inks and also
> doesn't give you good control over shadows...which is also critically
> dependent on balancing light black and black.  The dmax results that 
> I'm
> getting on RC papers are poor compared to what I'm getting using either
> imageprint or ink jet control.  In these cases colorbyte has carefully
> balanced the two inks and inkjet control, by giving you single channel
> control, allows you to balance them yourself.  In addition I'm getting 
> a
> strange type of wavy vertical banding from the QuadtoneRIP that I do 
> not get
> with the same printer using Inkjet control or Imageprint.  It isn't
> microbanding...you can't see it with a loupe...but it is easy to see 
> with
> your naked eye looking at a step wedge.
I've also noticed this, but only in step wedges printed at 2880x1440.
>
> Robert
>