Digital color control before proofing

1. Standardization of the color environment. The standardization of the color environment includes the standardization of the observation environment and the standardization of the ambient light source. This is the primary condition for implementing proofing color control. For the standardization of the observation environment, it is required that the color around the viewer (ie, the ambient color) and the background of the observed print (ie, the background color) be neutral gray, that is, the neutral gray of the Munsell value. Otherwise, the color of the environment or the background color is disorderly, which affects the viewer's judgment on the color. For the standardization of the ambient light source, a higher color temperature and a higher color rendering index are required. Currently recognized globally as light sources for reflection samples are D65 or D55, which have the same characteristics as red, green, and blue in the visible spectrum (360-750 nm), and their color rendering indices are all above 90.

2. Digital proofer linearization. Can you directly perform color management and proofing output after installing a digital proofing machine? The answer is no, linear proofing must be performed on the digital proofing machine so that it can always be in the best working condition. No matter if you change the nozzle or ink cartridge, the color of the printer will always be in the best state of standardization. The linearization of the digital proofing machine is based on the principle of measuring and adjusting the density of the linear patterns printed by the density meter or the spectrophotometer without correcting the color management. The basic linear correction of the printer is to determine the linear relationship between the input grayscale and the output grayscale, and to solve the difference in the color rendering characteristics, ink volume and density, ink volume and chroma performance of different inks on the print media. Keep the input and output values ​​in a basically linear manner, and adjust the proofing system to meet the criteria of the production standard.

3. Color management. In the color management of digital proofers, we need to pay attention to the following two points:

1 For color inkjet proofers, you must use original ink, otherwise it will affect the reproduction color gamut of digital proofing. This is due to the different color rendering characteristics of different printing inks.

2 The color gamut is related to the selected printing paper in addition to ink. Therefore, in addition to selecting high or semi-high gloss paper and matte paper as required, the most important point is that the color gamut printed by the color printer is larger than the color gamut reproduced by the printer using the CMYK four-color ink. Digital proofing makes it possible to simulate traditional proofing, which is the basis of digital proofing. The current color management color target is mainly IT8-73, which uses 928 color targets as the color control color target. It basically covers the common colors used for printing. The degree of digital proof color reduction is measured by its measurement parameters. .