Digital BW, The Print

QTR creates a greyscale from predetermined inks and then linearizes this
greyscale.  The process, in simple terms, is determine ink limits for each
component of the greyscale; print a calibration page which prints a
greyscale for each ink given the determined ink limits; measure the peak
densities of the lighter inks and determine where they sit on the K
greyscale, eg peak LK is 45% K, LLK is 15% K. QTR constructs a greyscale
using these inks, their limits and the partitioning points.  Print a
greyscale with this "ink curve".  Measure the L* and feed this info back
into the curve as a linearization function.  The maths behind the smoothing
of rolling from one ink to the next in the greyscale is hidden and well
beyond me.  So if one sets the ink limit of LK higher, all else being equal
it will print darker at peak and hence be 'partitioned' at a higher
percentage of K.


> From: dfaprinting <dfaprinting@...>
> Reply-To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
> Date: Wed, 13 Jul 2005 15:34:43 -0000
> To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
> Subject: [Digital BW] Re: Partitioning greys - an ink limit question
> 
> If you can give me a little more info, I might be able to help. This
> same thing comes up with the color channels too, even more so when you
> start using odd inks like I do.
> 
> What I need to know is, does QTR linearize each channel, and then you
> make the mixing partitions (resulting in a final linear "color"). Or do
> you make the mixes and then linearize that resulting "color". Sorry I'm
> not as familiar with QTR as I maybe should be, but I use a different
> RIP.
> 
> Obviously you want you full black to run up to full density (or your
> target density), so there isn't much to do there.
>