Using Gray-Balance Control in Press Calibration for Robust ICC Color Management in Sheet-Fed Offset

摘要

Coldest printers often use gray-balance fields for the adjustment and control of ink quantity during print runs. This method helps the printer to significantly reduce unwanted color cast in the printed product. A common way in sheet-fed offset to control the amount of ink is to decide upon target tone-value increase (TVI/dot gain) or density levels, with the intention to print the best subjective quality, even though the same quality cannot always be attained in every print run. Today, a predictable and equal quality is generally desirable, and therefore calibration and standardization are more in focus. Since there is no standardized way to calibrate a sheet-fed offset press, the possibility to produce an equal print quality in different print runs and printing presses is limited. Gray-balance control is a way to calibrate printing presses. The presses will always be set to print one standardized combination of CMY halftones in the same way. Hopefully, this will create a similarity between print runs, presses and to some extent paper qualities, which gives the foundation for robust ICC profiles. A study including print runs, evaluation of prints and creation of ICC profiles has been carried out. The use of gray-balance control in sheet-fed offset was primarily explored. It turned out to be possible to print without a color cast, and still keep print contrast, density, dot gain and CIELAB values for the secondary colors at an acceptable level. Prints on different coated papers were compared to investigate the similarities between these samples, when using this method and ICC profiles. The study showed that an ICC profile can give a similar print quality on different papers.