Integration of color management architecture and printing process

Foreword

The color management system has actually been talked about for a long time. From the early days of ColorSync 1.0 and 2.0 to the current ICC, the middle industry, academic circles, and users all spent a long time trying, exploring and using, but after this The long-term use of color management processes has not been as widespread as expected. Of course, although I can't propose a complete solution today, I can put forward some personal experience in use, and even some problems encountered in debugging, integrate it into a topic of color management architecture and printing process integration. Share with everyone.

Prof. Xu Mingjing

The basics and application architecture of color science

I. CIE World Color Standard:

The most important concept of the color matching function of CIE 1931 XYZ is to describe human perception of color in a mathematical way. In other words, everyone can use color perception in the existing CIE XYZ system. Three values ​​describe it. In the past, we were looking at colors. Unless we were looking at a single color in the same environment, it would be difficult to accurately define a "color." What was the difference in visual quality? It was too much under such conditions. Subjectively, there is no way to find a standard to define color. The problem we encounter in the printing industry is "customer first". Everything is measured by the customer's preferences. However, if the customer is color blind, quality control and communication of the colors will be difficult to achieve. Therefore, the CIE standard becomes very important. We can define the color of a metric as a measure to quantify the color.

Therefore, from the color matching function of CIE 1931 XYZ to the 1976 CIE LAB equidistant uniform color space, the meaning represented is that each color has a specific position in the color space. For example, we define red, orange, yellow, Green ... and other colors and white position in the color space, and where we copy the color in the color space, we can determine the color tolerance tolerance range, as a standard for future quality control. When creating tools for quality control in this way, the CIE LAB's isometric color space has practical significance.

Among the many CIE color standards, the most important concern is which one I should use, but it is important to say where your standards are in your manufacturing process, where you set your own, and you set the standards for everyone in the downstream industry. Where it is important, that is the standard that everyone communicates when they integrate.

Second, the use of printing industry

In the use of color management in the printing industry, there are actually many presuppositions, such as the standardization environment of the D50/2 degree perspective, as well as the different standards and different considerations of the color science in different industries, such as the considerations of the printing industry and the textile industry. There is a big difference. In terms of the instrument's considerations, there are also great differences. Can we say that the use of the instrument is not correct, but it is not good to blame the color management system. In fact, in the color management process, a certain link is not good, and not the color management process is not good.

Therefore, the color management process is based on the concept of device-independent color as a basis for color management. One of the most important concepts is whether the color value of your device's color in the color space can correspond to different materials in the color-independent space. The color value represented by one point, so you only need to map all the devices to the color space of LAB, and then the color space of LAB corresponds to another space, so that the color has a bridge for communication, and there is a way to install independent color space. Build color management.

Color management requires an exchange standard. We set the same standard and we can exchange color data with each other. This is the main task of ICC. ICC is actually a "spec", and you need to pay attention when you get a profile specification. The fact is that it is not compatible. It is something you should pay attention to when doing system integration.

Closed color printing process

The color electronic color separation machine and Drum Scanner have been used in color printing process for many years. For the printing process, there is an optimization process for personal equipment according to the personal machine. Under such a system, there is a very good separation quality, and the CMS The quality of color separation can only be less than or equal to the separation quality of Drum Scanner at most. CMS provides you with time saving, money saving and speeding up work flow, not replacing the separation quality of Drum Scanner.

However, Drum Scanner's color separation electronic color data is based on the back-end output device, printing machine, negative film output machine equipment into consideration, is a closed-color data, can not be used in a digital environment.

Color Management Architecture

The color management architecture contains three main programs:

1. Calibration

a. Calibration

b. Characterization

1. Color Profile

3. Transformation Engine (CMM)

Open Printing Process and Color Management Architecture

DTP and CTP lead to the introduction of an open sound brush environment and numerous color management systems/software hardware, and an integrated approach to color separation input and proofing The processes are all related to the color management process.

First, the color management printing environment:

To do color management requires the following instruments and components:

Color measuring instrument

2. Color management software

3. Integration of existing tools and existing production processes: Including existing computer operating systems, application software support, and output environment cooperation are the most important keys in the color management process.

Second, color input color management:

The RGB signals scanned by the scanner are converted into CMYK files for subsequent printing. We define it as the color management flow for color separation input.

So you must:

1. Create a profile for the input device

2. Set the input image original according to the profile established by the studio

3. Determine if the image file format is associated with Profile

4. Confirm the profile of the output device

5. Color correspondence and conversion of image data

6. Typesetting group page and output

Third, the separation of input considerations:

1. Scanner settings

2. Ideal for perfect manuscripts

3. Need for color correction/color gamut correspondence

4. Difficulties in sRGB, resulting in difficulties in use

5. How to integrate with RIP/Sever

6. How to evaluate the efficiency of the system

7. It can avoid the dependency of ink and other output characteristics

8. Still have a good output profile

Fourth, the color output of proofing

The color management required for proofing output needs:

1. Create a target profile

2. Establish a Profile Proofing Device

3. Absolute color conversion mode

Fifth, the proof output considerations:

1. The color gamut of the proofing equipment should be wide enough

2. The stability of the proofing equipment should be high enough

3. Non-four-color output characteristics

4. Differences in Black Replacement

5. Acceptability of FM network

Vision of the future

1. The theory of color management is feasible

2. Color management equipment continues to improve

3. Quality relative to expectations

4. Workflow needs to be adjusted and optimized

5. The education and training of personnel is the focus

6. Increasing productivity and reducing costs without affecting quality are goals.