QTR-Quadtone RIP

Carl,

Thanks.  His profile is basically just GG2.2 in RGB format so that LR recognizes
it.  The main difference in this profile is that it goes from L=0 to
L=100 -- there is
no reduced dMax.  I could also do this for Create-ICC but what you lose is the
softproofing with "simulate ink black" option.  This would pretty
certainly fix getting
a full dMax, but I'd have to check more to be sure of all the values
are corrected
properly.

Roy

On 7/10/07, Carl Schofield <list@...> wrote:
> Roy,
>
> Eric Chan made a custom icc profile available in the Adobe Lightroom
> forum.  His profile is for converting from gamma 1.8 to 2.2 in
> Lightroom and was designed for printing to the ABW Epson driver.
> Strangely, using this profile, instead of the Create-icc custom
> profiles, seems to also work well when printing to QTR from
> Lightroom.  Here is the link to download Eric's profile and the Adobe
> Forum thread where this is discussed:
> http://people.csail.mit.edu/ericchan/photos/tmp/GrayGamma22Print.zip
> http://www.adobeforums.com/cgi-bin/webx?128@@.3bc43829
> I think the rationale for doing this was that Epson ABW expects gamma
> 2.2 input and in Lightroom everything is gamma 1.8 (ProPhotoRGB).
> However, I don't understand why this profile would improve printing
> to QTR.
>
> Carl
>
> > Sorry for jumping in late -- I've been away for the last week.
> >
> > I've been trying various things with LR and color management.  It's
> > surprising that
> > its so different in many ways from Photoshop -- you'd think they would
> > capitalize
> > on their PS experience.
> >
> > It appears that when you print with a custom profile in LR that the
> > problem is not
> > lack of ICC conversions but double profiling.  Profiles have two
> > sets of curves
> > -- one for sending data to the print driver and the other for
> > displaying as in
> > softproofing.  The reduction in dMax indicates to me that what is
> > printed is similar
> > to a proof print.  I.e if you setup softproofing and enable Ink Black
> > Simulation you
> > get the same effect.   You can also see this happening if you take
> > an image in
> > PS, convert it to Gray Matte, and then convert it again to say GG2.2
> > without BPC.
> >
> > So my guess at this point is that LR is setting up a conversion to
> > your custom
> > print profile but that ColorSync later on is converting again -- (all
> > this is before QTR
> > ever sees anything).
> >
> > Input files also have some very interesting conversions happening
> > when you
> > import.   It appears that embedded profiles are honored but everything
> > is converted
> > to a linear gamma profile they call "Melissa RGB".  But when you look
> > at histograms
> > or R G B percents everything is again converted to sRGB.  All this
> > makes it
> > pretty mysterious when you try to figure out what to do.
> >
> > Printing targets for making ICCs is likely to be somewhere between
> > impossible
> > and tricky to know what gets to the driver.
> >
> > I'd be curious if anyone has info about the profiles for color
> > printing and the Epson
> > driver.  I'd think it may be tricky to get identical results from both
> > LR and PS.
> >
> > Roy
> >
> >
> > On 6/30/07, Carl Schofield <list@...> wrote:
> >> Walker,
> >>
> >> I think Roy will have to address that question, but I thought that
> >> QTR was relying on Photoshop to handle the front end icc conversion.
> >> I didn't realize that LR was passing the CM buck, but what you say
> >> certainly helps explain the problem.
> >>
> >> Thanks,
> >> Carl
> >>
> >> On Jun 30, 2007, at 5:57 PM, Walker Blackwell wrote:
> >>
> >>> I believe I just got to the bottom of it. Photoshop (it seems) does
> >>> all of the grunt-work when it comes to pure color management. That's
> >>> because it's been around since before OSs had any color management.
> >>> So when you print a big'ol image it's actually doing a hard-
> >>> conversion of that file to the out-put profile and then sending that
> >>> data along to the print driver. (Thus all the time it takes to
> >>> print.) All the print driver has to do is send the data to the
> >>> Printer.
> >>>
> >>> Lightroom, on the other hand, tags the image with the profile and
> >>> lets the print driver handle the conversion. I think that is where
> >>> it's getting sticky. This explains why I was having such a hard time
> >>> with the old Spro9600 drivers when printing color. They just
> >>> couldn't
> >>> handle the profile conversion themselves. The driver expected a
> >>> converted file.]
> >>>
> >>> It also explains the slight lag between finishing a file rip in
> >>> Lightroom and seeing it come up in the print queue.
> >>>
> >>> Can QTR handle ICC profile conversions? And is it v4 compliant? Most
> >>> likely more and more applications will come out soon that will
> >>> require OS and Driver color management instead of doing all the work
> >>> themselves. It makes everything faster and more scaleable.
> >>>
> >>> The nice thing is the Adobe CMM is open source and available to use
> >>> for such a thing as driver-based ICC conversions.
> >>>
> >>> take care, Walker
> >>
>
>
>
>
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