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SCCA (Substrate Corrected Colorimetric Aims)

Media-relative correction for substrate color.

 

ISO 15399 - 1.2
(DIS)  4.6 Adjustment of data for substrate color differences:
"The characterization data contained in ISO 15339-2 are all based on the CMYK characterization target defined in ISO 12642-2. The substrate color is therefore given in data element 1 of each data set.Where the printing substrate to be used has a color that differs from that of the reference printing condition selected for data preparation and data exchange by less than 2 CIEDE2000 the data may be used without modification.Where the printing substrate to be used has a color that differs from the characterized reference printing condition selected for data preparation and data exchange by more than 2 but less than 5 CIEDE2000 the method defined in Annex A (see also ISO 13655) shall be used to adjust the data before proofing and printing. Where substrate adjustment is done this fact, and the CIELAB values of the intended substrate shall be communicated to all involved."

 

SCCA Calculator is intended to calculate corrected characterization data whenever production substrate differs from the standard. It can also be used to convert data when a backing is not as specified in characterization data set. Most profiles/ characterization data sets are for white backing, but for double-side printing, we used to to measure on the black backer.

Adjustment method is based on principles defined in mention ISO standard. All necessarily characterized reference printing condition (CRPC) are available in the library.
The user has to select proper one, and input Two Lab coordinates:
- one for the substrate and one for a Minimal patch (Max TAC: e.g.100C 100M 100Y 100K) printed on selected substrate. Chromachecker's default is the value extracted from reference characterization data set.
It is recommended to input measured value if possible to improve accuracy.
Remember: All colorimetry should be defined to be ISO 13655 M1 with white backing. 

As a result, ChromaChecker SCCA Calculator returns new characterization data set in CGATS format,
a table containing primaries and secondaries coordinates and prognosis about a quality of data transformation.
Gamut plots  are used to visualize the difference between input and output data.
In some cases, mentioned method fails, and only one solution is to build custom ICC profile.
When the warning message appears building custom profile will be a finally cheaper method to achieve a goal. 

CGATS data produced by this tool can be used to build a profile for soft proofing substrate simulation,
hard proof and for corrected aims for the printing process.
As absolute rendering intent is used for this purpose, there is no need to convert data for plate making,
and this is enough to change only aims for process control.

 

The result of SCCA calculation can be as follows:





Gamut comparison graph shows what is going to happen with colorspace after SCCA calculation:




 SCCA is a formula for paper scaling developed by an American color scientist David McDowell,
a  member of the IDEAlliance Print Properties & Colorimetric Committee.

 

For more information consult: ISO/PAS 15339-1:2015