QA BULLETINS (click here to return to List)

TDPM C/M - PAPER MATRIX

1. OVERVIEW

The paper matrix procedure establishes a proper relationship between the paper response and the computer calculations. I.e. a succesful adaption will bring the yellow paper response to .16d per button, the magenta and cyan to .08d per button. In essence this is the same as establishing a paper gamma. However, the paper matrix is inclusive of the complete exposure system (Printlamps, IR Filter, UV Filter, Filter Unit, Measuring Block, Pre-filter, Light Integrator and Lens !!!)

2. PROCEDURE

Performing the TDPM C/M procedure will print 15 prints of a normal negative (after having balanced it to aim with TEST C/M).

The first 5 prints are from blue to yellow, while magenta and cyan should not change much at all.

The second five prints are from green to magenta, yellow and cyan should change little.

The third group of prints is from red to cyan, yellow and magenta should change little.

This line summarizes the deviation of the 3 neutral prints (print number 3, 8 and 13) from the PRD in the paper parameter. It is the densitometric correction that will be made to PAP when yes is answered at the end of the TDPM M procedure (equivalent to an automatic TEST C/M). Note that above is just an example.

3. EVALUATION

The Gretag manual suggests that the paper matrix should be repeated until the numbers at the bottom are +/- 0.02. However, the two colors that are not changing are also important, and should be within less than 0.04d variation before being satisfied with the matrix, regardless of the bottom line numbers (which will be much lower after repeated TDPM operations). The color response is adjusted so that a change of approximately .16d from one print to the next is achieved in the axis being tested.

To summarize:

• In the first 5 prints the magenta and cyan should not vary more than 4 points each.
• In the second set the yellow and cyan should not vary more than 4 points each.
• In the third set the yellow and magenta should not vary more than 4 points each.
• The summary line will probably be within +/- 0.005 or better if above guidelines are met.
• The color steps for the group (B/Y, G/M, R/C) should be around .16d the first step sometimes low, the last step sometimes high.

The paper matrix is now stored and will be used for all papers that are assigned to share it. Note that the PAP value will also be corrected for the normal (equivalent to a TEST C/M operation), so no other corrections should be entered when doing a TDPM.

4. VERIFICATION

Verification can be accomplished by plotting the results of a TROD 1 print sequence. When evaluating the Plot, all 7 prints should be within a spread of 0.06 x 0.06 (d) or better.

Plotting all iterations of subsequent paper matrix procedures will reveal how the matrix improves.

5. SHARING PMX WITH OTHER PRINTERS

According to Gretag, a paper matrix established on a given printer can be shared with others without having to run it again. This is, however, not the case as slope behavior of e.g. the filter unit may not be matched well. Specifically a set of yellow dichroic filters that are bleached will have less of a slope than new ones (which requires more movement to achieve a desired change). Also spectral characteristics of the Measuring Block, Light Integrator, Lens etc. come into play.

FINISys recommends that the PAPER MATRIX be established on each individual printer. Also different light integrators and or lenses may require a separate matrix (110 and stretch format).

6. ADDITIONAL INFORMATION

• FNS-QA-008 SETTING AIMS to 80 / 80 / 80
• FNS-QA-006 using TROD to EVALUATE PAPER MATRIX

This page last modified: May 08, 1997
copyright FINISys Inc. 1997, author: R. Ganahl