Digital BW, The Print

Roy,

thanks for all the details. A couple more q's: 

- Is it possible to do UnderColor Removal at the highest densities? (i.e. if you 
wanted only the black ink there and not (as much) of the others?). Since you 
don't control individual ink curves, it would seem not possible.

- Since the partitioning assumes all grays and a black, how can one play with 
toners (or is it possible at all?).

Sorry to be asking you all these questions, but I haven't had the time to play 
too much with OS X and/or install the QT RIP, so I am trying to get an 
overview.

In terms of dithering choices, did you just pick one of the gimp dithers, or is 
there a drop down somewhere for the end-user to play?

Antonis




--- In DigitalBlackandWhiteThePrint@yahoogroups.com, "Roy Harrington" 
<roy@h...> wrote:
> --- In DigitalBlackandWhiteThePrint@yahoogroups.com, "Antonis 
> Ricos" <antonisphoto@y...> wrote:
> 
> Antonis,
> 
> There are some similarities to IJC.  
> There's a calibration page that shows each individual ink in 
> a 21-step wedge laid out in percentages.  
> 1) You decide on ink limit percentages.
> 2) You print another page with your percents;
> 3) You just decide the order of inks -- dark to light and
>    measure the density of in terms of the next darker one.
>    This is just a density comparison -- absolute values are
>     not used.   You end up with percentages like:
>    Black = 100%,  Cyan=40%, Magenta=20%, Yellow=8%
> 
> This is all that goes into the partitioning algorithm.
> 
> After this you need to compensate for the dotgain.  This is
> pretty much like what IJC calls linearization, but you only
> have to do it for the already partitioned inks not the individual
> inks.  I have some aids for this where you specify how much
> "lightening" you need in the highlights and in the shadows
> and a smooth curve from light to dark is generated.   It's
> also possible to use Photoshop to make very steep dotgain
> correction curve, but for the most part that's not needed.
> 
> Roy
> 
> 
> > Roy,
> > 
> > 
> > at what point (and how) in this process do you make a profile? 
> > 
> > Antonis
> > 
> > 
> > 
> > ......
> > 
> >  One of the pages is a QuadToneRIP page where you
> > > select, first, that you want QuadTones, then select a curve or 
> two if you
> > > want blending.  Then print.  Naturally all these options that 
> you've
> > > selected can be saved as a named set for later use.  All the 
> data is spooled 
> > > and you're off working on the next image while that one 
> prints.
> > > 
> > > All this stuff works from any program that can have grayscale 
> images and
> > > can print.
> > > 
> > > Roy