Digital BW, The Print

Ernst, I'm sorry this went right by me at first

--- In DigitalBlackandWhiteThePrint@yahoogroups.com, "Ernst Dinkla" <
E.Dinkla@c...> wrote:
...
> use that setup for Ultratone VM inks. One of the decisions in
> curve control was whether the greys should be used to their full
> 100 % in each curve separation or let the next one take it over
> at 90 %. I think much of the softness, lack of small detail is a
> result of the right setting in that part of the curves and
> related to the dithering quality of the driver. If the dithering
> quality is excellent then you better end the curve early and let
> the next grey take it partly over with low percentage ink and the
> good dithering. The 90-100 % dithering is always harder to
> control than any dithering in the 0-30 % part.

The driver I use seems jumpier in the 90-100% areas, but I was unaware 
possible of dithering problems. Also, with some inks and papers, mottle 
and 
bleeding will result with a RIP that can pour ink down, that can 
certainly effect resolution.

>It is also a
> compromise on ink amount and the length of the greyramp covered
> by one grey. The Wasatch doesn't have such a good dithering and
> then the good compromise is harder to find. I still have to tweak
> that part better as I see the problems you describe.

There are actually many different variants possible with quad 
partitioning, it can get overwhelming.  A long smooth overlap between 
grays can be good and 
help with single channel banding in one situation, but maybe not take 
full advantage of a different printer. I think limiting each color is 
generally a good 
thing for many reasons, though I tend not to do it unless I have to (I 
use a large dot printer). One good reason is that I find paper batches 
vary more in 
where that critical mottle/bleed point is than in other ways, probably 
from coating variation. If you are not approaching that point, paper 
batches will look 
similar (I find). I'm right at that point, and have gotten some 
unusable batches.

> The work on the SoftRip neutral settings that I have done is as
> follows:

I'm not familiar with the inkset, but I'll try to follow. The only part 
I don't get is how you remain somewhat linear overall when introducing 
the toner. Do 
you have to go back to the CcYK curves and rework them to a lower gamma 
to make up for the addition of a given amount the toner? Mm sounds easy 
enough, it's just one channel. More or less M out of PS will take care 
of that since the Mm is linearized in the RIP right? But I don't know 
how you can 
have overall (but still linear) density control of CcYK. The blending 
options in OPM/IJC, the new R9 RIP, and the new Cone seem attractive in 
this regard.

> is on another XP system and I throw
> a simple straight CMYK 0-100% conversion of a greyscale file on
> it that is made with a PS action. Yesterday evening I got a small
> application that a friend has made which converts a 16 bit
> greyscale tiff into a plain 16 bit CMYK tiff (it has to be
> changed to LZW compression in default as that will make the files
> much smaller).

This is interesting. So you send it a full on 400% CMYK file and do all 
of the partitioning in the RIP?

...
> In the process I made a linearisation target that is dedicated to
> the Ultratone VM inks driven by the Wasatch. I have used
> Spectrocam readings as my Gretag densitometer is not reliable at
> higher Dmax anymore and the SoftRip is compatible with the
> Spectrocam.

I still use my Spectrocam for everything. One day it will explode and 
that will be that.  I've not seen the problems others have reported, 
though I'm not going 
for, or measuring Dmax's higher than pigment K on art papers.

> Another approach that is possible is the use of Paul's VM curves
> cnverted to RGB profiles and the Wasatch paper-ink settings
> adapted to the Epson driver. The Wasatch SoftRip can be made into
> an RGB device though it is CMYK in default. That would allow
> printing straight from a greyscale but I find it less transparent
> and I guess that I can get more in this way.

That's an interesting idea too. I wonder how well it would mimic the 
Epson driver. But you're right, it's more convoluted and you have less 
ultimate control.

Qimage sounds very interesting, and I wish there was a Mac version. Are 
you saying it limits black D?
That is the current problem with Gimp-print. I'm told the next release 
will allow much higher density, I find it too low right now. Roy's work 
with it is really 
great and still progressing, my testing with it is way behind. They 
need to get that density up though, for it to compete with other 
options.
Tyler