The Matters of Color Management

This article explains some issues and misconceptions that printing companies have in the color management process, outlines the workflow steps of color management, with the aim of reducing printing preparation time, minimizing waste, and improving production efficiency.

Keywords

Color management, color standards, color measurement, color difference, density

Main Text

In daily work, the author has encountered many printing companies that have complex feelings about color management – some love it and hate it at the same time, some highly praise it, and some think it is useless... So why is there such a huge difference of opinion? Next, let's discuss some misconceptions about color management:

1. Company A said that for the same printing file, reprinting could not match the colors and required file and plate modifications. Upon investigation, it turned out that their prepress plate setter had not had its developer replaced or cleaned for a month, the developing temperature was unstable; they did not use measurement instruments to monitor whether the halftone dots met standards, and sometimes did not monitor at all.

2. Company B is very busy with production and has no time to maintain the printing press, so the press keeps running. As long as the press works, they consider the condition good. The result is that the printed color is unstable, there are large color differences at the sheet overlap, the dot gain is significant and very unstable.

The original intention of color management is to use color management tools to reduce printing preparation time, minimize waste, and improve production efficiency.

However, the opposite often occurs: even with significant investment of manpower and resources, the results are not obvious and fall far short of expectations. Why is that?

Many times, our understanding of color management is somewhat one-sided. Some think that installing digital proofing in prepress is color management; some think that conducting CIP3/4 connectivity for prepress printing is color management; some think that adjusting the plate curve is color management...

In fact, color management is a systematic project. It requires close cooperation between prepress and printing, through a series of inspection instruments and collaboration with color management software, to establish color standards and perform regular maintenance to achieve the set standards.

As shown in the picture above, this is a flowchart of color management that I have summarized, which outlines the process of color management.

Next, let's take a closer look:

01

At the top of the chart is the printing color standard. It can be a color standard customized by our own factory, a target standard required by the client, or an international standard, such as ISO 12647-2. The subsequent workflow of color control revolves around this target.

02

Once the target is determined, the prepress process begins. First is soft proofing to match the printing standard. By calibrating professional monitors and loading ICCs for color deviation correction and printing standards, the color displayed on the screen is made consistent with the printing color standard.

03

The prepress digital proofing system consists of a wide-gamut printer, color management software, and color measurement instruments. The printer prints color patches such as TC1617, and color measurement instruments like i1iO (as shown below) detect the colors of the patches. The data is fed back to the color management software and compared with the target printing colors. If the color deviation exceeds the tolerance range, the software adjusts the color proportions according to the deviation values. Then, a second print is made... this closed-loop cycle continues until the digital proofing matches the printing standard.

04

Whether it is soft proofing or digital proofing, regular testing and correction are required to ensure that the color is consistent and matches the printing standard. If the color is not up to par or unstable, consider changing the printing conditions to make it compliant.

05

After both soft proofing and digital proofing meet the standards, we need to test the printing plate. Pay attention to two points, one is to standardize the prepress publishing operation and lay the printing plate curve, so that the deviation of the printing plate outlets is within the tolerance range, such as the deviation does not exceed 0.5%. The second is to conduct regular testing to ensure that each printing plate meets the standards, and once a problem is found, it is necessary to deal with and eliminate the problem in a timely manner.

06

Then there is the standardized management of the printing press.

The first is the standardized management of the dampening fluid: PH value/conductivity/alcohol ratio/water tank temperature and other parameters. The second is the standardization of the ink transfer system: including whether the state of the water and ink roller is up to standard, whether the pressure of the ink roller is up to standard, as well as the bearing state, ink stringing parameters, etc. Then, the parameters of the blanket are standardized: the elasticity, hardness and elasticity of the blanket after a long time. Includes special or general paper for the liner (backing paper) under the blanket. Blanket surface roughness/surface hardness (too high is easy to appear "bulging", "bar", etc. when printing, too low can easily lead to graphic deformation) / thickness loss rate/print resistance rate...... etc. Others, including registration function, ink tank and ink bond function, water tank refrigeration and wetting liquid circulation and replenishment function, etc., must be qualified for standardization and standardization.

Only after the internal standardized management of the printing machine, quantifying the indicators, and meeting the standards can the printing standard matching of the printing machine be carried out in the next step, which is meaningful.

07

Next, the printing standard of the printing machine is matched.

We first test whether the color difference of real colors such as CMYKRGB meets the standard by printing test versions. If it does not meet the standard, it is necessary to consider the replacement of ink and paper. Secondly, by obtaining the correct dot enlargement and gray balance plate curve, the plate is reproduced to obtain the correct dot enlargement and gray balance. Finally, through the cooperation of the printing machine, color management software, and color measuring instruments, the color printed by the printing machine is matched with the printing target. Record the standard density and obtain the ICC of the press.

08

The first press completes the printing standard matching, next, we have to do lateral operation, the second, the third... The method is the same as the first, however, pay attention to the following:

1. The expansion of the outlets of each printing machine and the correct management of the gray balance printing plate curve, do not wear a crown.

2. Clearly and correctly manage the network correction curve of the prepress publishing machine and the printing machine network expansion and gray balance plate curve, understand their functions, and do not use mistakes.

09

Maintain the consistency of printing conditions: such as printing materials such as ink and dampening solution, pre-press printing plates, development, ink, digital printing paper, etc.; operation methods, such as printing color sequence, etc.; The brand of the paper, etc. Changes in printing conditions during the printing process, including prepress, will affect the success or failure of color management.

10

As with prepress, after completing the printing standard matching of the printing machine, the machine should be regularly maintained, and the standard management of the printing machine should be carried out, and the parameters should be met and quantitatively monitored. It is necessary to regularly carry out the matching work of the printing standard of the printing machine, correct the deviation, verify the matching with the printing standard, and maintain the matching of the printing standard.

11

On this basis, in order to improve production efficiency, we connect CIP3/4 and generate pre-inking curves according to printing standards, so that the pre-inking is efficient. In addition, scanning and closed-loop systems can also be installed (as shown in the figure below): the scanning system detects the difference between the current color and the target parameters, and the closed-loop system intelligently adjusts the ink keys of the printing press via computer to quickly reach the target color. This reduces paper waste, improves production efficiency, and enhances color quality.

Summary

In summary, regarding those matters of print color management, I hope everyone can effectively carry out this systematic project of color management, with each link connected, forming an efficient and accurate color closed loop, in order to achieve the goals of improving color quality, reducing waste of paper, ink, and labor, and enhancing work efficiency.