QTR-Quadtone RIP

I have been using the QTR Create-ICC tool for about a year and am pretty comfortable with the process. Recently I attempted to use the Create-ICC-RGB tool so that I could embed a color curve that I have developed for using UT14 ink on glossy paper. This curve works very well if it is manually loaded and then the image is printed using printer controls and gamma 2.2 settings. Creating an ICC for this would allow me to print the image without the Photoshop add-curve step, print out of applications other than Photoshop and embed a more accurate grayscale ramp. 

When working through this I realized that my methodology (which works pretty well) for the Create-ICC calibration step of the process was wrong. I have been using a pasted-in 21-step scale added to the scanned image as a layer, not a scanned Q-13 calibration scale scanned with the printed stepwedge. I don't recall why I changed from the process described in the instructions. 

When I realized this, I changed my process and began following the instructions precisely, adding the Q-13 to my scan and then setting the calibration panel for 20 steps, middle gray at step 7 and using the default Lab values. The result of doing this is that all my created ICCs print terribly dark with maximum black beginning at around the 15th step in the 21-step scale. No messing around with the Lab values in the calibration setup box seems to correct this. 

I went back and read many of the articles that have been written about this process. I paid particular attention to Paul Roark's article http://www.paulroark.com/BW-Info/Making_B-W_ICCs-1.pdf. In this article,  Paul discusses the Q-13 scale and notes that paper black is at the B mark, not at the 20th step. 

What I am wondering is:  When I use the Q-13 scale, should I be selecting only the steps 0-16 before starting the Create ICC script and setting the calibration panel settings to a 17-step ramp (A to B) with middle gray at 7? 

Could calibrating off of the blacks that are darker than paper black be throwing off my calibration?

My experience with these flatbed methods led me to conclude that the main
thing that needed to be corrected was the general shape of the flatbed
curve ("gamma" is a term I used in the PDFs).  To do this, the Kodak gray
card (Lab L=50) was the easiest to use if doing this manually.  Thus I
simplified the PDF noted below by making this one:
http://www.paulroark.com/BW-Info/Making_B-W_ICCs-GrayCard.pdf .  One could
do the same thing by using just the mid-gray point ("M") on the Q13.  Then,
all you have to worry about is the midpoint and the ends of the 21-step
test strip that was scanned (not the Q13).

In general, since Roy has now automated the process of using the full Q13
in the QTR StepWedge Tool (see
http://www.quadtonerip.com/html/QTRdownload.html ), I recommend using that
system and its excellent PDF instructions for the best flatbed control with
the full Q13.  For the manual method, I'd stick with the simple three point
adjustment approach of
http://www.paulroark.com/BW-Info/Making_B-W_ICCs-GrayCard.pdf .

Paul
www.PaulRoark.com



On Mon, Dec 10, 2012 at 7:37 AM, remononaz1 <homershannon@...> wrote:

> **
>
>
> I have been using the QTR Create-ICC tool for about a year and am pretty
> comfortable with the process. Recently I attempted to use the
> Create-ICC-RGB tool so that I could embed a color curve that I have
> developed for using UT14 ink on glossy paper. This curve works very well if
> it is manually loaded and then the image is printed using printer controls
> and gamma 2.2 settings. Creating an ICC for this would allow me to print
> the image without the Photoshop add-curve step, print out of applications
> other than Photoshop and embed a more accurate grayscale ramp.
>
> When working through this I realized that my methodology (which works
> pretty well) for the Create-ICC calibration step of the process was wrong.
> I have been using a pasted-in 21-step scale added to the scanned image as a
> layer, not a scanned Q-13 calibration scale scanned with the printed
> stepwedge. I don't recall why I changed from the process described in the
> instructions.
>
> When I realized this, I changed my process and began following the
> instructions precisely, adding the Q-13 to my scan and then setting the
> calibration panel for 20 steps, middle gray at step 7 and using the default
> Lab values. The result of doing this is that all my created ICCs print
> terribly dark with maximum black beginning at around the 15th step in the
> 21-step scale. No messing around with the Lab values in the calibration
> setup box seems to correct this.
>
> I went back and read many of the articles that have been written about
> this process. I paid particular attention to Paul Roark's article
> http://www.paulroark.com/BW-Info/Making_B-W_ICCs-1.pdf. In this article,
> Paul discusses the Q-13 scale and notes that paper black is at the B mark,
> not at the 20th step.
>
> What I am wondering is: When I use the Q-13 scale, should I be selecting
> only the steps 0-16 before starting the Create ICC script and setting the
> calibration panel settings to a 17-step ramp (A to B) with middle gray at
> 7?
>
> Could calibrating off of the blacks that are darker than paper black be
> throwing off my calibration?
>
>  
>


[Non-text portions of this message have been removed]

I have been using the instructions you reference at http://www.quadtonerip.com/html/QTRdownload.html. They are very clear and I'm following them precisely. Still, I'm getting ICCs that print way too dark. 

I re-examined your Lab values for the Q-13 that you have posted at http://www.paulroark.com/BW-Info/Making_B-W_ICCs-1.pdf and realize that I was confusing the Lab values with the density values. The instuctions in QTR are consistent with your notes. 

My scans don't seem to be wildly off, so I just don't understand why the ICCs created following the QTR instructions using the Q-13 calibration scale always print overly dark. 

--- In QuadtoneRIP@yahoogroups.com, Paul Roark <roark.paul@...> wrote:

>
> My experience with these flatbed methods led me to conclude that the main
> thing that needed to be corrected was the general shape of the flatbed
> curve ("gamma" is a term I used in the PDFs).  To do this, the Kodak gray
> card (Lab L=50) was the easiest to use if doing this manually.  Thus I
> simplified the PDF noted below by making this one:
> http://www.paulroark.com/BW-Info/Making_B-W_ICCs-GrayCard.pdf .  One could
> do the same thing by using just the mid-gray point ("M") on the Q13.  Then,
> all you have to worry about is the midpoint and the ends of the 21-step
> test strip that was scanned (not the Q13).
> 
> In general, since Roy has now automated the process of using the full Q13
> in the QTR StepWedge Tool (see
> http://www.quadtonerip.com/html/QTRdownload.html ), I recommend using that
> system and its excellent PDF instructions for the best flatbed control with
> the full Q13.  For the manual method, I'd stick with the simple three point
> adjustment approach of
> http://www.paulroark.com/BW-Info/Making_B-W_ICCs-GrayCard.pdf .
> 
> Paul
> www.PaulRoark.com
> 
> 
> 
> On Mon, Dec 10, 2012 at 7:37 AM, remononaz1 <homershannon@...> wrote:
> 
> > **
> >
> >
> > I have been using the QTR Create-ICC tool for about a year and am pretty
> > comfortable with the process. Recently I attempted to use the
> > Create-ICC-RGB tool so that I could embed a color curve that I have
> > developed for using UT14 ink on glossy paper. This curve works very well if
> > it is manually loaded and then the image is printed using printer controls
> > and gamma 2.2 settings. Creating an ICC for this would allow me to print
> > the image without the Photoshop add-curve step, print out of applications
> > other than Photoshop and embed a more accurate grayscale ramp.
> >
> > When working through this I realized that my methodology (which works
> > pretty well) for the Create-ICC calibration step of the process was wrong.
> > I have been using a pasted-in 21-step scale added to the scanned image as a
> > layer, not a scanned Q-13 calibration scale scanned with the printed
> > stepwedge. I don't recall why I changed from the process described in the
> > instructions.
> >
> > When I realized this, I changed my process and began following the
> > instructions precisely, adding the Q-13 to my scan and then setting the
> > calibration panel for 20 steps, middle gray at step 7 and using the default
> > Lab values. The result of doing this is that all my created ICCs print
> > terribly dark with maximum black beginning at around the 15th step in the
> > 21-step scale. No messing around with the Lab values in the calibration
> > setup box seems to correct this.
> >
> > I went back and read many of the articles that have been written about
> > this process. I paid particular attention to Paul Roark's article
> > http://www.paulroark.com/BW-Info/Making_B-W_ICCs-1.pdf. In this article,
> > Paul discusses the Q-13 scale and notes that paper black is at the B mark,
> > not at the 20th step.
> >
> > What I am wondering is: When I use the Q-13 scale, should I be selecting
> > only the steps 0-16 before starting the Create ICC script and setting the
> > calibration panel settings to a 17-step ramp (A to B) with middle gray at
> > 7?
> >
> > Could calibrating off of the blacks that are darker than paper black be
> > throwing off my calibration?
> >
> >  
> >
> 
> 
> [Non-text portions of this message have been removed]
>