Application of color measurement in printing

Printing Control During the offset printing process, the thickness of the ink on the paper changes as the ink flow in the ink fountain increases. The ink density, the process control, was set on the press and was previously observed with the eye. But over the past decade, color measurements have been made using density measurements. Standards developed using densitometer measurements are SWOP, SNAP, and GRACoL.

Quality Control (QC)
Quality control includes the following functions: monitoring the process control of the press, monitoring the consistency of the print, and tracking production variables. Printing operators are most concerned about printing density and dot gain, and further analysis is based on ink overprint conditions, print contrast, color difference, and gray balance.

Measurable production variables affecting image quality include: the film dot area of ​​the image-setter, the size of the print dot of the printing plate or the CTP plate. To measure these variables, the QC department has a densitometer or spectrophotometer for the printing plant.

Because of the low contrast of the image and non-image portions, there are measurement problems when using densitometers to read data from CTP or conventional media. BetaScreen and Tobias claim that they have optical densitometers that can accurately read the data on the plates.

The new generation of media readers are based on video CCD-based devices such as ACME Media Reader and Centurfax CCDot, both of which are marketed by the Beta company in the United States. These instruments use a video array of approximately 250*300 dots to determine the dot area on the plate, unlike the light reflectance principle used in densitometers.

The desktop production process allows desktop operators to use spectrophotometers or colorimeters to test chromatograms, user materials, and colors on photographs. ColorMovieToo! by Color Savvy, Specrolino by GretageMacbeth, DTP22 by X-Rite, and Colorton can all be used for this purpose. use. Using an optical radiation colorimeter or spectrophotometer with a screen calibration software, the operator can calibrate the screen color. X-Rite's DTP92 Monitor Optimizer and CretagMacbeth's SpectroScan can be used for this purpose.