QTR-Quadtone RIP

--- In QuadtoneRIP@yahoogroups.com, "David Meddings" <meddings@f...>
wrote:
>
> Quick followup on my own issue:
> 
> Trying various dithering algorithms with 1440 super or 1440 (both at 
> the better setting) had no effect.
> 
> Printing at 2880 got rid of microbanding but introduced major bronzing
> 
> Adding 12.5% monochromatic gaussian noise to the shadows and printing 
> at my normal settings solved the problem.
> 
> So thanks to Tom Moore and indeed it looks as if there is an issue in 
> the gimp printing side of things.

Very much so. The gimp print drivers will exhibit microbanding
whenever the total ink density (just all all 7 channel curves) exceeds
100%. This is easy to do with a glop curve, since we're typically
adding glop at anywhere from 10-25% to curves that might have an ink
limit at 80%, or black boost up to 100%.

I'm working on a driver with a layering concept as part of GRIP (if
GRIP ever hits the point of being a useful public beta). The glop
would go on an "aligned" layer so glop droplets always end up on top
of colored ink droplets.

gimp print always interleaves ink, nothing ever really overlaps, and
you cannot exceed 100% coverage (inks just displace each other, which
can be a really, really weird looking effect when glop displaces black).