Some published measurement data sets, specifically those for CRPC1 through CRPC7, represent print conditions that are G7 grayscale compliant. However, profiles created from these data sets produce significant cast errors in the G7 Cmy0 (press neutral CMY, with K=0) ramp, as shown below, on the graph blue line. The error appears in the device profile and is visible on printed output. If you look at the Cmy0 ramp from paper white to 100 CMY, the Cmy0 ramp appears warmish, then coolish, then warmish again.
With the cast errors, the color space can still pass G7 requirements; however, the visual appearance of the ramp is poor. This effect can be seen in the CIE L*a*b* measurements of the output (see the a*-b* graph below on right). The blue line shows the cast error: the patch color shifts from “warmish” (higher a* value) on values below 50% neutral gray, to “coolish” (lower a* value) on values from 50% neutral gray to 85% neutral gray, then back to “warmish” from 85% to 100%. The yellow line with gray dots shows the expected Cmy0 Ramp behavior.
To correct the CRPC device condition cast errors, 2 changes are needed:
- New data sets that contain the target CIEL*a*b* for the Cmy0 ramp, and
- New Profile Creation software to make use of the new Cmy0 datapoints.
Kodak has created new data sets, and source profiles, named as follows:
New Data sets:
o ColdsetNews_CRPC1_neutral.cgt
o HeatsetNews_CRPC2_neutral.cgt
o GRACoL2013_Uncoated_CRPC3_neutral.cgt
o SWOP2013_SC_CRPC4_neutral.cgt
o SWOP2013_Coated3_CRPC5_neutral.cgt
o GRACoL2013_C1_CRPC6_neutral.cgt
o UniversalXL_CRPC7_neutral.cgt
New Source Profiles:
o CRPC1_Neutral.icc
o CRPC2_Neutral.icc
o CRPC3_Neutral.icc
o CRPC4_Neutral.icc
o CRPC5_Neutral.icc
o CRPC6_Neutral.icc
o CRPC7_Neutral.icc
Kodak’s core color technology engine has been upgraded to make use of the new data points (Kodak ColorEngine build 4664 and higher). This new technology is available to customers through the following software products:
- Kodak ColorFlow 9.0.3 and higher, and
- Kodak Proofing Software (KPS) v10.0 and higher
For the best color performance, it is recommended to replace the CRPC data sets and profiles with the new ones listed above, whenever possible.