Digital BW, The Print

Roy Harrington wrote:
> 
> --- In DigitalBlackandWhiteThePrint@yahoogroups.com, "ldina" <lbdina@c...> wrote:
> 
>>Roy, I was curious if you found the LAB Grayscale profile effective 
>>and if you updated your original profile?
>>
>>I'm probably missing something, but it seems this would have to be a 
>>generic profile by its nature.  If used for viewing the tonal range 
>>on a monitor, how would it be able to differentiate between a high 
>>gamut glossy paper (like Kirkland Glossy which can hit an L* of about 
>>6) to lower gamut matte paper that can only display an L* or about 
>>20?  
>>
>>Seems to me they would both display the same, but the output would be 
>>very different.
>>
>>If you have found it effective, I'd love to know how you use it and 
>>how you handle different paper types.  I'd also like to get your 
>>latest profile if your results are positive.
>>
>>Thanks, Lou
> 
> 
> Hi Lou,
> 
> I have been experimenting with this.  I find the Lab gray space better than
> the gamma space.  At least I find the separations are better matched to the
> print and to the eye.  But you are right about how different papers are
> enough different that you can't switch back and forth without editing.
> 
> My current take is that the gray Lab space is best for editing, but that there
> should be a way to do a mapping with perceptual intent rendering at
> print time.   I think it's possible to have just a few profiles -- i.e. a
> generic matte paper and a generic photo paper -- rather than making
> a gazillion profiles for every combination.
> 
> Roy

Roy,

Is what you propose not already done in most RIPs (but in
colour mode) ?  The linearisation of the channels separate of
the profiling, the last to the Lab space/axis. In that way you
could use the LittleCMS or Argyll engine for profiling. The
fastest way now would be to use either Photoshop or Qimage and
a B&W adapted ICC profile. Qimage makes RGB print to file
output, as long as the greyscale isn't corrupted but only the
steps shifted along the curve it would be right. Doesn't
provide the right preview on color (tones) but the rest in an
acceptable way. The linearisation takes care of the paper +
printer + ink differences. The Lab curve goes on top of that
and you could probably limit them to the two choices you
mention, one covering up to 1.7 Dmax, the other to something
like 2.1.

Ernst