Digital BW, The Print

Hi Didzis,


>... problem ... with blocked shadows when printing 
>with icc that have been created from your curves as 
>per embedding Photoshop curves instructions. 
>The inkset is UT7, printer Epson 2100 
>and I am using the PrintFix Pro spectro. Latest version 
>of Quadtone RIP. 

> ... my icc creation process ...

Looks OK.



>1) When printing Paul's ... curve ...

With my curves on the AdobeRGB version of the file, your 50% test patch has
a Lab L of 61. That's a bit light.  A strictly linear response, which is
close to what the curves were originally made for, would be half way between
the paper white and 100% black.  That point is L = 56. (Note that my old
target was density = 0.61, which would be about L 56.6.)

>I create the ICC profile ...

>Then I print the same GG 2.2 21-step wedge from PS using 
>the newly created profile ...
>The shadows get blocked up and the result is much 
>LESS linear using ICC than it would be using simple curves ...

Yes, Gray Gamma 2.2 is not linear and the old curves target was more linear.
But the ICC should -- if the monitor is calibrated and the systems are
working right -- make a print that matches the monitor better than the old
curves.  Most of us used some method of overriding the usual gray spaces
such as a custom dot gain curve or the like to better match the monitor to
the prints.

With the ICC, your 50% patch is L = 54.  I think that's about right.

In fact, with the ICC the ramp is very linear to 90%.  Then the problem is
that 90% to 100% has very little separation.  The 50% to 100% usually has
very little separation in Gray Gamma 2.2.  The 90% to 95% is, however, less
than I would expect.  I'm guessing that the Create ICC RGB program is simply
working with too little information about what is going on in the deep
shadows.  It's probably assuming a straight line response between the 95%
and 100% input points when, in fact, the output gets much darker sooner than
the program assumes. 

I'm not sure if the Create ICC programs will accept 51 step inputs, but most
of QTR will.  That might get enough information to the program to correct
the problem.  Be sure to print the target vertically, as I've found it more
accurate that way.  


>... I do not quite understand the approach that you 
> suggested to Daniel by using a correction layer, 

If a file was edited for a linear output and is then printed in a Gray Gamma
2.2 space, the shadows will be crushed.  A correction layer is just a way to
use older files (edited for linear spaces) in GG 2.2 (or vice versa) without
having to re-edit the files.  I wish all our workflows, spaces, etc. were
consistent, but they just are not.  

If the curves work for you and match your monitor, then by all means stay
with that workflow.  I think, however, for most people it would be easier to
stay with a standard gray working space like GG 2.2 and use a workflow that,
at least ideally, should match the print to a calibrated monitor without the
need for any special layers or soft proofing procedures.

>Unrelated issue I have is that my Windows XP appears to 
>have problems recognizing these icc.

True, only Photoshop and Elements print previews recognize these grayscale
ICCs.

> I copy the icc manually into windows icc directory - but 
>even then Photoshop only recognizes the icc only after I 
>"repair" the file name/internal name mismatch error that 
>these profiles have.

Is this the extension problem with the old GTE ISP?  That is, have you been
able to download the ICC with the *.icc extension in tact, yet you still get
this error?  If the latter, I'm not sure what the problem is.

I've changed the link in the UT7 readme files now to go to the new ISP.
Hopefully the extension problem will be corrected now.  To download use
normal procedures -- right click, save as -- not extension correction shoud
be needed.

Paul
www.PaulRoark.com