G7™ calibration without Color Management - Does it work?

Author: David Hunter, Krzysztof Kućma, ChromaChecker Corp.

Test parameters:

• Printer: Epson Stylus Pro 4900
• Substrate: Epson Standard Proofing Paper 206
• Instrument: X-Rite iSis XL
• Calibration Chart: P2P25Xa
• Visual Test Form:  ChromaChecker CRPC-7 (CGATS21_CRPC7.icc)
• Calibration software: Alwan Print Standardizer 5.1.1
• Color server: Alwan ColorHubX 4.1.0 
• RIP: ColorBurst 7.4

Question:

Can G7™ Calibration be applied without Color Management? Does it work?

Procedure:  

G7™  calibration of Epson Stylus Pro 4900 

1. Two documents: P2P25Xa Test Chart and Chromachecker  CRPC-7 (CGATS21_CRPC7.icc)  has been printed on Epson Stylus Pro 4900 with Color Management switched off on the printer RIP. 
2. Alwan Print Standardizer 5.1.1 has been used to drive X-Rite iSis XL to capture P2P25Xa and generate  TRCA (Tone Reproduction Curve Adjustement)
   
   
   
   
3. In Alwan ColorHubX a new queue has been defined: Task Settings: the only one active task:  Print/Press Calibration based on imported TRCA curves.
   
   
4. Test page:  Both P2P25Xa Test Chart and CRPC-7 (CGATS21_CRPC7.icc) had been processed with a new queue, next printed on Epson 4900 again with CM switched off on the RIP. 
       
   Original P2P25Xa file (left side) and the same file processed with Print/Press Calibration Task on ACH (left side). Comparing columns number 4 and 5  tone reproduction adjustment can be observed. (input files - not result of printing)
   
     
   In uncalibrated (left side) pictures grays are not neutral, but saturated colors have strange hues. After  G7™ Calibration (right side) grays become neutral, tonality slightly tuned. Black and wite pictures are very good, but all saturated colors have the wrong hue. Tomatoes become orange not red, corn, grass and skin tones of baby face - are too yellowish
   
5. Visual comparison of both P2P25Xa before (left side) and after G7 ™ calibration (right side)
   
   Comparing 4 and 5 columns (red rectangle)  before and after calibration is easy to observe that calibration works correctly (scans of printed pages)
   
   
6. Visual comparison of CRPC-7 Test Form (CGATS21_CRPC7.icc) before and after G7™ Calibration
   
           
   
   Original file (left side) and after G7™ Calibration.  To compensate neutrals are more reddish, shadows lighter – scans of the printouts.
   
   
7. Original File has been reprinted with Color Management turned on.

Three printed Test pages had been compared original with CM on (left side), original w/o CM  ( in the middle) and G7 Calibrated w/o CM ( right side):

Comparision of G7™ calibrated only (left side) and Color Managed picture (right side) – scans of the printouts.

Conclusion:

G7™ Calibration applied without Color Management is not able to control Primaries and Secondaries Solids - All saturated color are not managed, and the final result can differ from original very much, but in the same time gray balance is corrected and tonality partially improved. 

Additional analysis:

Primaries ∆E and ∆H: