Digital BW, The Print

--- In DigitalBlackandWhiteThePrint@yahoogroups.com, "Bob Marsolais" <bob@...> wrote:
>
> --- In DigitalBlackandWhiteThePrint@yahoogroups.com, "Roy Harrington"
> <roy@> wrote:
> >
> 
> > There is one other issue with grayscale handling.  Some editing,
> image processing
> > programs themselves do not handle grayscale image files.  This
> includes some 
> > majors ones like: InDesign, Lightroom, Aperture and Qimage.
> 
> I asked Jonathan Saks, the author of PictureWindowPro, whether PWP
> recognized gray scale ICC's.  His answer was, "No it does not.
> However, a gray profile is just a curve."

In a sense that's true.  It's a curve that maps K (as is Photoshop) values to Luminosity
or Luminance values.  The regular gray profiles like gray gamma 2.2 or dot gain 20%
or anything else map the numbers in a file to Luminance values.   The curves are all
similar but they are different.   Take a stepwedge or any image and just start assigning
different profiles to it -- you'll see the difference in luminance on the screen.
The QTR-Create-ICC grayscale ICC profiles also map K to L but based on actual 
measured values rather than idealized curves.  The big plus of color management
is that it can convert one curve mapping into another curve mapping in an automated
standard way.   You could go into Photoshop Adj Curves and accomplish the same
thing but you'd be doing it again for every combination of input and output.

Real color profiles are a bit more involved since they are 3 dimensional mappings.

> 
> I keep seeing the mention of ICC's with imbedded curves.  (I don't
> think this is what Jonathan meant, IMO.)  Is an "ICC with imbedded
> curves" an ICC plus a curve or a completely self-contained ICC?  What
> is meant by "ICC with imbedded curves"?

I don't know for sure where you saw this but I did some special work for a version
of Create-ICC that incorporates some photoshop .acv adjustment curves as well as the
grayscale mapping I mentioned above.  This is pretty non-standard usage but it
fit into the ICC format and helped convert much of Paul Roark's hand done .acv work
into a ICC managed workflow.

Roy

> 
> Thanks, Roy and Tobie, for the very enlightening conversation!
>