November 30, 2021

Road Map for Extended Color Gamut printing

A. Requirements are:

  1. Documenting all primary and secondary variables related to print process
  2. Calibrating CMYK using G7, calibrating OGV colorants via SCTV
  3. Characterization of print condition(s)
  4. Conversion from any color space (RGB, Spot, CMYK, ECG, Etc) to any color space
  5. Conformance- Ensure the ECG result matches the ECG Profile used in conversion

B. Recommendations for

  1. Substrate tracking
  2. Lighting, and 
  3. Instrument Harmonization

1. Documentation

Document all relevant press variables- this step is critical before creating an ICC Profile for the press since each of these variables, if changed, will affect the performance of the ICC Profile to the point that it will not produce accurate results. It is critical that each of these variables is tracked before the profile is created to understand the normal condition of the press. And each variable needs to be assessed after the profile is created to ensure consistency of press matches the condition when the profile was created. 
  1. ECG inks should be drawn down on respective substrates to ensure the Lab values will match the ink vendors' targets. 
  2. Screen angles and screen types need to be defined and documented to ensure repeatability.
  3. The print sequence needs to be defined and documented to ensure repeatability.
  4. Cylinder pressure for all units
  5. Plate imaging (either linear or raw)
  6. Instrument precision
  7. Temperature and Humidity
  8. Fountain solution variables- temperature, PH, conductivity, Brix, other
  9. Ink stripe digitally measured for all units

2. Calibration

(This can be handled by ChromaChecker Inspectors)

  1. Process CMYK- Perform G7 Methodology for press without dedicated press runs to ensure G7 Curves are appropriate. 
  2. ECG Colors — The CxF-X4 target should be imaged any time a potential candidate ECG primary color is run on press for each substrate. This target is small and can be aligned with the ink key to ensuring the consistency of tints. Position as many of these CxF-X4 targets on actual jobs as possible to create a complete characterization of the ECG inks.
  3. Use ChromaChecker Print Condition Qualifier to determine how many substrates have to be individually calibrated based on the plant's expectations. This step determines how many G7 Curves or ICC Profiles have to be created to accommodate multiple print conditions (different substrates, surface characteristics), and how many can be shared eliminating unnecessary time and energy calibrating conditions that can be shared with others.
  4. Trend the characteristics of the press performance for spectral values for CMYK solids and their respective TVI to attain the desired G7 Condition. It is imperative that press operators understand that they must hit the required densities and TVI for all primary colors within the press, especially when additional 5-7 primaries are added.
  • Export the MeasureColor data as a Print Standardizer text file for each press condition into separate directories that can be uploaded into ChromaChecker to track the CMYK values
  • Add CXF/X4 templates to live jobs printing the ECG inks whenever it is possible on all important substrates, collect these measurements over time to track the consistency and reproducibility of the ECG primaries


3. Characterization

(This is where Alwan Hydra is used)

  1. Use multiple Alwan Hydra Characterization targets in line with actual customer work when printing ECG jobs
  2. Use CxF data captured with ChromaChecker in Alwan Hydra to build the appropriate ECG profiles
  3. Use the GRACoL_ECG reference profile as the source profile in your proofing devices to provide a reference for ECG work for a given substrate.


When all the above has been accomplished, then the Alwan Hydra XYZ patch target should be positioned in live work and run in multiple positions on the press sheet and samples should be taken throughout the press run. Samples that do not have primaries at the right Lab values should be eliminated from the average.
*** CC has the ability to ingest these measurement files, eliminate the biggest offenders and build an average data set from the rest that can be exported to Hydra to create the profile.


4. Conversion

Customer workflow needs to support ability to convert PDF from any color space to any color space to ensure the appropriate colors are mapped to ECG channels as necessary to accurately match the reference color.

This is where the Alwan ColorHub or GMG Color Server comes into the workflow to ensure colors are mapped optimally


5. Conformance

(Measure and assess the resultant ECG Color for color matching to reference to ensure the print is salable.) 

Using an appropriate color bar with at least 60 different patch values optimized for the print process to ensure the color will meet expectations.

  1. Critical to ensure the actual print process matches the ICC Profile used to convert the files, if they do not match, unpredictable results will happen, and customer expectations will not be met. It is imperative that the output matches the workflow for predictable color results. Any change in the process will cause the color to change, and not meet expectations.

Recommended addition steps

  1. Substrates to be profiled should be measured into Substrate inspector which assesses:
    • OBA Index
    • Gloss
    • Opacity
    • Thickness
    • M1 Whiteness

      With the supply chain causing paper shortages, it is critical to benchmark the paper used for ICC Profiling in order to understand that if you need to change to a different paper, what the ramifications will be on your existing ICC Profile performance. 

  2. All Light booths should be assessed for ISO-3664:2009 compliance and should be compared to one another to ensure users looking at the same print in different light booths are viewing the same color.

  3. Instruments should be baselined and assessed for precision using Instrument Inspector to ensure all instruments are measuring in an accurate predictable manner. If the goal is to measure the ICC Profile using the KM FD9, then a comparison should be made between the press Intellitrax instrument and the FD9 to understand the error difference between the two instruments. The H-100 target can be used to compensate for the differences and better align the press measurement values with the ICC Profile measurement values. 

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