QTR-Quadtone RIP

--- In QuadtoneRIP@yahoogroups.com, Ernst Dinkla <E.Dinkla@c...> wrote:
> Tyler Boley wrote:
> 
> >--- In QuadtoneRIP@yahoogroups.com, Ernst Dinkla <E.Dinkla@c...> wrote:
> >...
> >  
> >
> >>I think that using 
> >>more heads + less dilutions of black  ink + effective use of droplet 
> >>sizes and actually using the mix you get from heads weaving (as intended 
> >>in the printer design) will in the end deliver less banding, better 
> >>linearisation, more consistency in time. I have written this before in 
> >>relation to BO printing and on the K7 threads.
> >>    
> >>
> >
> >Are you speaking of using different density K inks in parallel rather than 
partitioned series, 
> >or some combination of the two?
> >We discussed this once before, I thought the BO users could benefit from a the 
more 
> >complex dither that would result. I never got the chance to test it. Life is getting 
too short 
> >for all this testing.
> >Actually, can you assign two inks to the same part of the scale in QTR?
> >  
> >
> 
> I've used a quad setup on the 9000 that had the Eboni black + the middle 
> grey ink in the Mm channels and was linearised like that and in the Cc 
> channels, the darkest grey + lightest grey ink in Mm and linearised like 
> that again. Some partitioning was laid on top of that, (the highlights 
> were done by the lightest range only, mixing of the two ranges was of 
> course mainly in the mid ranges, 2% of the darkest grey went up with the 
> black) trying to get as close to native linearisation and an overall 
> linearisation etc added afterwards. Wasatch SoftRip. That's a simple 
> example of what I propose. BTW, Paul Roark's PS curves and ink mixes 
> must have had a similar structure.
> The crudest example is having 4 black inks in a C86 for BO, that will 
> give you a nozzle quantity that comes near 360 if I recall it correctly.
> On a K7 printer and with QTR you could make one K4 range and a K3 ink 
> range, linearise them and mix them with the slider. The 5 partitioning 
> points of the two ranges are all overlapped, and you get weaving of two 
> heads on any spot. Depending on the droplet sizes available (resolution) 
> and the partitioning the droplet size transfer points could overlap as 
> well. If you use the normal K7 inks then you would expect more visible 
> dots in the highlights but I think it will not be much more visible. You 
> will loose the possibility to mix toner in but that's not available in 
> the K7 set anyway. No need to change inks. Ink distribution may benefit 
> from the original CMYK weaving positions though, for example the K3 in 
> the CcY lines the K4 in the KkMm lines. In a way these overlapping quads 
> resemble the B&W films with two or more emulsion layers.

There's certainly lots of ways to make curves for the inkset.  A 7-way partition
is probably the most obvious but the interleaving of 2 separate sets makes
some sense.  In fact one person I know is interleaving K with 3 grays from K7
for one set and K with 3 piezos for the other set.  Then you can blend for
different tones.  But two sets from the K7 would work and maybe you may
have a point on it being better for linearization.

> 
> I have no idea how the K7 inks are distributed on the ink positions, if 
> they use the two main lines as sketched above and given that the overlap 
> in the partitions is already relatively wider as one head only covers 
> about 14% of the total range, the result may be close to having two 
> ranges next to one another. The ink distribution something like K7-K, 
> K6-C, K5-k, K4-c, K3-M, K2-Y, K1-m. If that's happening already then I 
> shouldn't worry about the K7 concept.

There are just 7 shades, partitioning overlaps a lot as it is.  But if more 
overlapping would probably happen with the interleave idea. 

> 
> No,  I don't think you can assign two inks to the same part in QTR, I 
> have asked that once and got an answer by Carl or Daniel but couldn't 

I'm not sure what you want either but there is now a COPY_CURVE function
that can dup any curve for multiple inks.

> figure it out or my question wasn't understood. I think it would be good 
> if QTR allowed the use of multiple heads for the same task.

Not sure if it's a benefit or not.  A counter-argument is that you would have
less diversity of dropsizes.  I think that diversity of dropsizes is particularly
beneficial to eliminating banding.  Actually its most important to use drops
that are big enough to merge between lines when the density gets darker.

Roy

> 
> Ernst