Calibrating, Printing and Proofing by the G7™ Method

Calibrating, Printing and Proofing by the G7 Method Version 6, August 2006
Glossary
calibration, printer Adjusting a printing device to a known and repeatable condition - typically by using
consistent substrate and colorants, and by adjusting tonality, gray balance and other
metrics to a constant measurable state
Characterization data A file of CIELab or CIEXYZ or spectral measurements of a printed target from which,
if the corresponding colorant values of each patch (e.g. CMYK percentages) are also
known, an ICC profile can be created
CIE (Commission Internationale de l'Eclairage) an international group formed in the early
20th century (still active) to study and numerically define human color vision.
Described as follows at www.cie.co.at/cie;
"..an organization devoted to international cooperation and exchange of information among its
member countries on all matters relating to the science and art of lighting. The CIE is a
technical, scientific and cultural, non-profit autonomous organization. It has grown out of the
interests of individuals working in illumination. Since its inception 90 years ago, the CIE has
become a professional organization and has been accepted as representing the best authority
on the subject and as such is recognized by ISO as an international standardization body."
CIEXYZ A standard CIE color space expressed in variables X, Y and Z, corresponding to the
'visual matching functions' derived from the original CIE color vision experiments
CIELab (CIEL*a*b*; Lab) A standard CIE color space derived from CIEXYZ where L* = Lightness, a* = the
green-red vector and b* = the blue-yellow vector in a mathematically cubic space
CIELCH (LCH) A more visually-intuitive interpretation of he standard CIELab color space in which a*
and b* values are replaced by the radial vector C (Chroma or saturation) and the
angular measure H (Hue)
CMY Cyan, Magenta and Yellow
CMYK Cyan, Magenta, Yellow and Black
Colorimetric Based on CIE color science (as opposed to densitometry)
CtP Computer to Plate - a plate making system which eliminates the need for intermediate
positive or negative films
D-50 Industry - standard viewing light color expressed as a complete spectral energy
distribution curve
Delta-E (Delta-E*, ∆E*ab) Standard CIE formula for expressing a color difference between CIELab readings.
Several improvements exist, including ∆E*94, ∆E*CMC and ∆E*2000, but the original
formula;
∆E*ab = (∆L* 2 + ∆a* 2 + ∆b* 2 ) 0.5
Density Log10 (1 / reflectance)
Dot Gain See 'Tone Value Increase'
is simplest to calculate and adequate for the purposes of this document.
Fogra www.fogra.org- German Graphic Technology Research Association whose purpose is
to promote research into, and the development and application of printing technology,
and to make the results available to the printing industry.
G7 The GRACoL7 calibration and press control method. 'G' denotes the focus on
'Grays', while '7' refers to the seven colorimetric ink values of Cyan (C), Magenta (M),
Yellow (Y), Black (K), Red (M+Y), Green (C+Y), and Blue (C+M).
GATF Graphic Arts Technical Foundation - provides (amongst other services) ISO 2846
laboratory ink testing
GRACoL www.gracol.org- Subsidiary group under IDEALliance - stands for General
Recommendations for Applications in Offset Lithography
GRACoL 7 Seventh edition of the GRACoL document and specifications
Gray (Grey) A tone or image element without any visual chroma or color. The universallyaccepted
spelling 'Gray' is adopted in preference to the equally-acceptable 'Grey' due
to simple phonetic logic. (Samuel Johnson has a lot to answer for!)
54 Copyright © International Digital Enterprise Alliance, Inc. [IDEAlliance] (2006). All Rights Reserved.