Digital BW, The Print

I have had and still have the same trouble understanding the QTR ICC 
effect. In essence my understanding of a traditional icm is that it 
reflects/includes both the printer-paper-ink caracterization and the 
conversion needed to map from one space to another thus including the 
needed linearisation calculation. In the case of QTR caracterization 
and linearization are done in the QTR curve creation process and 
curves are called from the printing interface (this is why curves are 
refered to as profiles in the manual and the soft). So while at this 
first stage you can't proof you do have a linear output.

ICC generator adds accurate soft proofing without a doubt : 
Well,to me at least, and it seems to be the feature Roy wanted to 
add, this would, to me again, explains why before the Generator he 
created a gray-lab space and generic mat/photo grey icc in the hope 
one would go for a first basic soft proofing ability, but I tend to 
believe BP and WP were then only generic and not describing the real 
ones while he probably wanted true soft proofing with actual BP/WP.

Back to the new ICC, it can also serve a conversion in PS from RVB to 
Grayscale. Besides, from memory, using this Grey ICC as a printing 
space profil also produces a B&W image from a RVB colored file in the 
OEM driver (though I did not print, I just visualised the preview). 
So I would tend to conclude it is a true ICC generator that can be 
used like any other profile except that instead of mapping source 
space colors to destination space "available" colors it maps s.s.c. 
to destination space grey values, probably only retaining the L* 
values to do so. And Roy recently informed he wants to provide full 
icc support including colors to reflect toning and white paper color 
if I'm not wrong.

Now since the read target is an already linearised stepwedge (this is 
how I understood you have to create the ICC not from the non-linear 
setpwedge), the profile just becomes a description of the printer-ink-
paper BP and WP with evenly distributed grey values.

This is where I am confused and additional testings need to be run :
1. convert a RVB file with the grey profile and send it as such to 
the Epson driver or print with "print space" profile being the grey 
icc to measure linearity. If unlinear (and it must be) the profile 
simply act as a PS grey mode action in this direction.
2. Create a profile from the non-linear stepwedge and use it in the 
destination space profile from an RVB file : though it will 
demonstrate nothing but the linearisation is achieved by the profile 
and could serve in ABW mode for instance.
3. print with QTR with and w/o converting to the profile (oh yes I 
run Windows as an OS) adn mesure the stepwedge.

I understood that without QTR, the EOM driver will interpret whatever 
comes gray into a CMYK output thus blending the color ink in a non-
linear way (the same with a quadtone setting). So the whole QTR 
profile generation would turn to be mainly a soft proofing feature : 
whether you convert or not a gray file before sending it to QTR will 
have no effect (as long as you create the profile from the linear 
stepwedge).

If not wrong in the above, the "better" B&W experienced using a QTR 
ICC would come from teh fact that actual BP and WP would have been 
measured and grey values re-distributed accordingly, proving QTR ICC 
provides a true B&W profiling feature.

But still they are questions :
1. Do you need to(or should you) use this profile when printing with 
QTR for anything else than softproofing ?
2. Would you consider converting a RVB file into a Grayscale one in 
PS using this profile ?
3. Would you use it in an ABW workflow with a 2400/4800... and if so 
do you create from a linear stepwedge or non-linear one in the case 
of the 2400 ?

I'm sorry all this sounds confused and probably repeating part of 
what Steve wrote, but to me... it is very confusing.

Now one question to Steve :


>In the current
> incarnation of the Grey ICC profile generator, Roy is doing the 
black point
> compensation rather than leaving it to PS (this is why you can't 
proof for
> the weaker print black at the moment).  

This I don't understand : "can't proof the weaker print black" ? In 
the (little) testing I did I would have said the proofing also adjust 
the BP. This would also be demonstrated by Roy's instruction 
mentionning you need to soft-proof using perceptual and BPC (the BP 
being thus embeded in the grey ICC). I'm sure I wrongly understood 
the sentence.