QTR-Quadtone RIP

I am having a challenge.

I am in the process of re-creating a set of curves due to some  
changes in density after a recent service call.

I have traditionally had difficulty overcoming the below-explained  
issue but have either dealt with it or "tweaked" around it.




Bear with me, this is a lot of detail but I think it would be a good  
exercise to document this for public consumption.


I am creating two curves, using Cone Piezotone inks.
Each curve will be a partition of 4 inks

Carbon Sepia Curve: Museum Black, Carbon Sepia Dark, Carbon Sepia  
Medium, Carbon Sepia Light

Selenium Tone Curve: Museum Black, Selenium Tone Dark, Selenium Tone  
Medium, Selenium Tone Light


Environment:
	- Mac OSX 10.4.8
	- QTR version 2.5

	- Photoshop CS2

	- Epson 7600
		Piezotone inks
			Museum Black
			Carbon Sepia set
			Selenium set.

	- Hahnemuhle Photo Rag 308


Process:
1) Print the InkSeparation.psd file
	No color management when opening
	No color management when printing
	Printed in Calibration mode
	Calibration Ink Density 100%

2) Dry the print

3) Find the first point in Black scale where we reach total ink  
coverage.
	Visually and with a Densitometer
	I determined the Default Ink Density should be 50% (Density 1.7 read  
with Xrite 810)

4) Reprint the InkSeparation.psd file with same settings except  
Calibration Ink Density set to 50%

5) Dry Print

6) Determine partitioning values for ink overlap for
	a) Point where 100% density of Carbon Sepia Dark intersects with  
ramp of Museum Black
	b) Point where 100% density of Carbon Sepia Medium intersects with  
ramp of Carbon Sepia Dark
	b) Point where 100% density of Carbon Sepia Light intersects with  
ramp of Carbon Sepia Medium


The following table displays densitometer reading of every patch.

Ink 1 - Black - Unlimited    00     05    10    15    20    25     
30    35    40    45    50    55    60    65    70    75    80     
85    90    95    100
Museum Black - Unlimited    0.05   0.54  0.88  1.13  1.34  1.48   
1.56  1.61  1.66  1.68  1.70  1.71  1.72  1.72  1.73  1.73  1.73   
1.72  1.71  1.71  1.72

     Reprint with Calibration Ink Limit set at 50%

     Readings from resulting print:

Ink - 1 Black (limited)  0     5    10    15    20    25    30     
35    40    45    50    55    60    65    70    75    80    85     
90    95    100   Overlap   Calculated values
Museum Black (40%)      0.05 0.33  0.54  0.74  0.91  1.02  1.12   
1.25  1.35  1.44  1.49  1.53  1.57  1.60  1.62  1.65  1.66  1.68   
1.68  1.69  1.70   100.0%      100.0%

Ink 2 - Cyan             0     5    10    15    20    25    30     
35    40    45    50    55    60    65    70    75    80    85     
90    95    100
Carbon Sepia Dark       0.05  0.18  0.29  0.39  0.48  0.56  0.63   
0.70  0.77  0.84  0.89  0.95  1.00  1.04  1.08  1.13  1.15  1.20   
1.23  1.26  1.28   36.5%      36.50%

Ink 3 - Magenta          0     5    10    15    20    25    30     
35    40    45    50    55    60    65    70    75    80    85     
90    95    100
Carbon Sepia Med        0.05  0.11  0.15  0.20  0.24  0.27  0.32   
0.35  0.40  0.44  0.47  0.50  0.54  0.57  0.60  0.62  0.66  0.68   
0.70  0.73  0.75   38.0%      13.87%

Ink 4 - Yellow           0     5    10    15    20    25    30     
35    40    45    50    55    60    65    70    75    80    85     
90    95    100
Selenium Light          0.05  0.08  0.09  0.11  0.13  0.14  0.16   
0.18  0.20  0.22  0.24  0.26  0.27  0.29  0.30  0.32  0.33  0.35   
0.36  0.38  0.38   48.0%       4.92%

Ink 5 - Light Cyan       0     5    10    15    20    25    30     
35    40    45    50    55    60    65    70    75    80    85     
90    95    100
Selenium Dark           0.05  0.16  0.23  0.31  0.38  0.45  0.51   
0.58  0.64  0.69  0.74  0.79  0.83  0.87  0.90  0.93  0.97  1.00   
1.02  1.04  1.07   27.0%      27.00%

Ink 6 - Light Magenta    0     5    10    15    20    25    30     
35    40    45    50    55    60    65    70    75    80    85     
90    95    100
Selenium Med            0.05  0.10  0.13  0.17  0.20  0.23  0.27   
0.30  0.33  0.36  0.39  0.42  0.44  0.47  0.49  0.51  0.54  0.56   
0.58  0.60  0.62   38.0%      10.26%

Ink 1 - Light Black      0     5    10    15    20    25    30     
35    40    45    50    55    60    65    70    75    80    85     
90    95    100
Carbon Sepia Light     0.05  0.08  0.10  0.12  0.14  0.17  0.19   
0.22  0.23  0.26  0.28  0.30  0.32  0.34  0.35  0.38  0.40  0.42   
0.43  0.44  0.46    48.0%       6.66%


7) Create a new Ink Descriptor file for Museum Black plus the three  
Carbon Sepia inks
    - I am not currently at the computer that has the file on it to  
include all of the data, but I inserted the proper VAL= entries in  
the proper inks.

    For reference I used the following other values

    GRAY_HIGHLIGHT=10
    GRAY_SHADOW=10

    GRAY_OVERLAP=
    GRAY_GAMMA=1
    GRAY_CURVE=

8) Created curve via "Drop-Quad-Profile"

9) Print a 21 Step file
	- Opened without color managing
	- Printed without color management
	- Selected the proper Curve file
	- Made sure I was using 100% of the curve
	- No other curves were selected

10) Dry Print

11) Read 21 patches from resulting print

     Readings shown below

       0    05    10    15    20    25    30    35    40    45     
50    55    60    65    70    75    80    85    90    95    100
     0.05  0.33  0.54  0.74  0.91  1.02  1.12  1.25  1.35  1.44   
1.49  1.53  1.57  1.60  1.62  1.65  1.66  1.68  1.68  1.69  1.70


     Notice the flat spot between 85% and 95%

     These values prevent a successful linearization


11) Just for grins I "tweaked" the 85% reading to 1.67 to create  
enough difference to process the linearization.


12) Print a 21 Step file
	- Opened without color managing
	- Printed without color management
	- Selected the proper Curve file
	- Made sure I was using 100% of the curve
	- No other curves were selected

    (Should I be choosing a document profile and a Printer Profile  
here?)

12) Analyze print

	The result was unacceptable.
	Everything looks great except between 95 and 100% there is a sudden,  
hard drop to max density


13) I re-did the Linearization process using an Eye-One with the 51- 
Step-Random file and MeasureTool
     I kept getting "Linearization failed - values do not..." (I  
can't recall the exact verbiage, but you know the one.)
     I opened the file in Excel and did some hunting.
     I sorted the data by L-density and found two lines that seemed  
out of whack

14) I re-read the values from the print again to rule out user error  
in the patch-reading process.
     Again, I got the "Linearization failed - values do not..." error
     I opened this new file in Excel.
     I sorted the data by L-density and this time found FOUR lines  
that were out of whack (not the same ones as the first time)

15) I decided to try to "tweak" the density L values in the first  
file to make them conform and got the "QTR-Linearize-Data" process to  
work.
	I then dropped the file on "QTR-Create-ICC" and successfully created  
a profile

16) I printed the 21 step file, choosing my freshly minted profile.
     This time everything looked very good.

Sooooo....

17) I followed the same Eye-one Process for Museum Black and the  
three Selenium inks
     New Print of 51 step Random
	Dry Print
	Read in MeasureTool
	Save file
	Drop on "QTR-Linearize-Data"
	Again, I got the "Linearization failed - values do not..." error
	However, when I opened the file in Excel to analyze, I noticed that  
the value for 100% was quite a bit different than the 95% patch. So  
different that I cannot tweak it in good conscience.

Given that the highest density of the darkest Selenium ink is 1.07  
versus 1.28 for the darkest Carbon Sepia, should I set the ink limit  
for the Selenium inks to 100% and re-partition, or is there an error  
somewhere in my process?

Any advice is gladly accepted.

James Haney


















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