QTR-Quadtone RIP

Hi Ferdinand,

On Dec 16, 2007 6:34 PM, ferdinand_paris <ferdinand_paris@...> wrote:

> Qu.1:  This thread started buy asking what type of file to drop onto
> QTR-Create-ICC[-RGB].exe. I have a related question.  I print the
> target and measure it and I get a text file from the MeasureTool.  I
> drop this target onto QTR-Linearize-Data.exe to get the linearisation
> data.  So far so good.


Yes, the operation is simply drop a text file on to one of the programs.
QTR-Linearize-Data is for making/linearizing a QTR profile/curve.
The other two are for making standard ICC profiles.


> But if I want to create an ICC profile, is it this exact same text
> file that I also drop onto QTR-Create-ICC[-RGB].exe?  Or is it a
> second text file that I get from printing and reading a target printed
> *WITH* the newly derived linearisation data?


The procedure looks very similar but there is an important distinction.
You always first create a QTR profile/curve UNLINEARIZED, print out the
target with
the unlinearized curve, then read data, run QTR-Linearize-Data, and put the
data
into the curve thereby linearizing it.

The ICC scheme is builtin on top of a linearized QTR curve.  So you've
already done
the above.  Now print out the target with the linearized curve, read the
data,
run QTR-Create-ICC (or RGB version).  You now get a standard ICC profile.
What you've just done is "profiled" the QTR driver with a specific curve and
settings.

(this may look a little like double-profiling which is a no-no but it's not
at all true.
 the first run is to make a standardized (i.e. linear) print driver.  the
second is to
 profile that driver as in ICC color management).


> I've read the three pdf help files and trawled the archives, and this
> point is not entirely clear to me.  They read like I should use the
> first text file, but when reading the very useful file "ICC Info.txt"
> by Roy in the files section, it suggests that ICC profiling is in
> effect profiling the QTR driver.  This suggests to me that I should be
> using the second text file derived from printing a target using a
> linearised curve, non?


Yes, as above.


>
>
>
> Qu.2:  I created both grey and RGB ICC profiles and stored them in the
> correct folder, but when I opened Photoshop I saw only the grey
> profile.  I discovered that this is because although the two profiles
> have different file names, they have the same internal profile name.
> Is this intentional?  I would have thought that the RGB profile would
> have "-RGB" appended to its internal name.
>

You are right, they have the same internal name. I guess I didn't figure on
both being
used.  Photoshop apparently will just show one of them -- I only see the RGB
one.


> Qu.3  How many people are printing via Qimage, and are using its CM
> options to convert to a QTR profile, and how many others are doing
> profile conversion prior to reaching Qimage?


I don't use Qimage so haven't kept up with changes that may have occurred.
If there's any problem or doubt about the ICC conversion doing it in
Photoshop
should solve the problem.   It's very easy to make another generic profile
that
does the same as QTR-RGB Matte Paper -- this may solve any BPC issue.
(Just put "16 96" in a text file and drop it onto QTR-Create-ICC-RGB).

I'd like to hear from anyone whether this helps with Qimage, if so I'll
change
the generic in the next release.

Hope this all helps.
Roy


>
> By way of background, I was around when Roy & Mike first got Qimage
> recognising QTR ICC profiles, but have been largely absent from the
> debate since then.  Like Ernst, based on experiments that I did at the
> time, I tend not to trust Qimage's CMS for B&W.   I've re-read the
> archives in this forum on this topic, and particularly from around the
> middle of the year.  It seems to have a lot to do with rendering and
> BPC.  The quote from Roy below seems important. Is it as simple as
> using BPC for the generic QTR profiles, and not using it for custom
> profiles?
>
> Ferdinand
>
> --- In QuadtoneRIP@yahoogroups.com, "Roy Harrington" <roy@...> wrote:
> >
> > (I should mention that the generic QTR-Gray Matte/Photo Paper
> > profiles were done as XYZ matrix profiles and do not have the BPC
> > builtin -- they depend on the CMS).
> >
> > Roy
>
>
>


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