Digital BW, The Print

OK I understand but I am not trying to compare my colour managed results
with Carl's. (I haven't even done an HPR AB&W print using colour
management.)  I was principally concerned with comparing the GM colour
profile vs the QTR create ICC profile.  The point was to do a very rough
cross check on your BPC and to show that the sort of impact at the black end
of the scale of the QTR Create ICC profile is consistent with what a GM HPR
colour profile does, ie it would appear to be behaving correctly.  (I was
disappointed the Epson colour driver did not get the same min L* to make the
comparison more direct.) A great deal of comfort is gained if we see a
performance consistent with the colour community's widely deployed colour
management.  Then it is also valid to compare the linearised un-managed
output (ie the workflow prior to QTR Create ICC) with ICC profile managed
output - not the actual points (which for two of the charts are influenced
by my GG 2.2 workspace) but the "general" shape of the TRC. That is to say,
as expected, colour management compresses the dark end of the scale and
generally lowers the L* of the TRC.

Re Carl's work, I have simply noted the very tight compression in the
straight non-colour managed output.  If he is printing an untagged document
without colour management then he is sending unaltered pixel values
presumably with the observations he intends.  (My desire to confirm the
document isn't tagged in  anyway is to ensure that, say, a 95% step is
actually 95% K etc.)  He observed only a 0.77 difference in L* between 95%
and 100%.  My Adv B&W printout (without colour management) on the 4800 shows
an L* difference of 3.08 between 100 and 96 and 4.7 between 100 and 94.
Hence my question as to his choice of paper setting.  For HPR I used Velvet
Fine Art and I wondered whether if he used this paper setting the ink load
etc may provide less bunching in the dark end. This isn't anything to do
with colour management but rather the basic performance of the 2400 Adv B&W
driver.  BTW Carl I am using Eboni in the K slot which I think is another
difference.  I agree our colour managed observations are not comparable
because of the different workspaces.  His 50% patch would be seeking an L*
of 50 vs my 54.


> From: Roy Harrington <roy@...>
> Reply-To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
> Date: Fri, 21 Oct 2005 22:57:51 -0000
> To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
> Subject: Re: [Digital BW] ICC v. Transfer Function in Epson driver
> 
> 
> I hate to beat this to death but once you select a printing
> profile in the Print with Preview -- there is NO SUCH THING
> as UNTAGGED RAW DATA.  If there is no embedded profile it will
> use the Working Gray Space.  It has to have a source profile in
> order to apply the print profile.  It's never one-sided.  There
> no such thing as converting a raw file into a print profile.
> 
> So if you guys compare results when printing with ICC profiles
> the source profiles make a difference and if you see Untagged
> then the working space is critical.
> 
> Roy