QTR-Quadtone RIP

I began using the LINEARIZE command three or four years ago for my QTR profiles for digital negatives and did not have any issues with the basic work flow, which is as follows.

1. Open a 21 or 51 step target, convert it to a negative, and print on OHP. Use the same print settings you plan to use in printing your negatives, including of course No Color Management.

2. Using the step wedge negative make a positive print in your process, using you standard process controls.

3. Scan the positive step wedge print with a spectrophotometer or colorimeter, beginning at the lightest step and ending with the darkest one. Save the .txt file.

4. Drop the .txt file on the QTR-Linearize-Data application, and the Linearize numbers will be created. Two sets of numbers are generated, one for direct printing of positives, a second reversed set for printing digital negatives.

5. Insert the Linearize sequence in your QTR profile. For example.
LINEARIZE="19.5 20.76 22.12 23.32 23.98 26.61 27.8 28.77 30.31 31.95 33.04 34.01 36.41 37.57 39.03 41.4 42.63 43.75 46.79 48.73 50.27 51.43 52.4 53.36 54.67 55.67 56.41 58.57 60.34 61.61 63.59 65.74 67.37 70.14 71.12 72.49 73.85 75.2 76.76 79.49 80.81 82.85 85.17 86.87 89.44 91.06 93.03 93.63 94.01 94.66 95.3"

(Alternatively, if you use a densitometer you can just read the log densities of the step wedge print, from lightest to darkest, and insert them directly into the QTR Profile.)

6. Run the Install Command for your Quad printer, then check the Terminal script to make sure that the profile was installed. If the values are not increasing as the program expects you will get a command "Invalid Linearize Command -- Not Constantly Increasing." This can be confusing because sometimes the numbers are constantly increasing, but apparently not enough to satisfy the program. To verify that the profile was installed go (for MAC) Library>Printers>QTR>Quadtone>QuadYourPrinter. Click on the specific .quad file to see it in graph form.

Finally, both LINEARIZE and GRAY_CURVE= can be used in the same profile. This can be very useful because you can have one profile that is linearize for a process with LINEARIZE, then linearized for specific variations of the process with GRAY_CURVE=.

If you have been using GRAY_CURVE in the past for digital negatives for alternative printing and attempt to switch to LINEARIZE the biggest issue you will have is not the digital work flow, but process control. You can make GRAY_CURVE= work by fudging the curve, which can be way off and still work. But for LINEARIZE to work with Lab values you must have 21 discrete values ranging from light to dark, and the values must be constantly increasing enough to satisfy the requirements of the program.

Sandy