Spectral Dimension
A three-dimensional color space standard represents color through mathematical values of lightness and chromaticity. In print production, cie lab color defines the visual appearance of printed ink on paperboard independent of the specific device used for output. The axis L denotes lightness on a scale from zero to one hundred, while the parameter a tracks greenness to redness and the parameter b tracks blueness to yellowness.
Using these three coordinates, color matching becomes an objective calculation rather than a visual approximation. Spectral instruments measure these coordinates to establish a clear digital target for press operators, who use the resulting numbers to align different production batches with the original approved reference.
Measurement Practice
Press control depends on precise measurement of printed paper substrates under standardized illumination. In this workflow, cie lab color readings are captured using a spectrophotometer configured with a standard D50 illuminant and a two-degree observer angle. This specific configuration ensures that the measured data corresponds to standard daylight viewing conditions.
Surface gloss and stock texture influence the light reflectance, making consistent instrument pressure and backing material necessary for repeatable numbers. Operators rely on these values to adjust ink film thickness or modify ink formulations during a production run.
Industrial Deviation
Industrial requirements dictate a tolerance limit for color drift between approved proofs and production runs. This drift is calculated as a single delta E value, which represents the geometric distance in the cie lab color space. Brand owners commonly enforce a delta E tolerance of less than two.
