Establish a color management system with its own characteristics

Color is the life of color printing, improve color printing quality, we must first improve the color quality. The process of copying a color image is, in the final analysis, the process of copying the color. It is to convert the analog document through the color decomposition of the scan or the digital document through the color space conversion process, and then transfer the screen to the printing through the output film, printing plate or CTP direct plate making. Color synthesis, to restore the original purpose. Practice has proved that: In the entire quality management and control chain of printing companies, color management is at the center, color is the core of print quality control, whether the normal operation of the color management system directly determines whether the purpose of quality management can be achieved, and also determines production operations. Can it go smoothly?

At present, many printing companies have failed to establish an effective color management system and have poor color control. They cannot meet the requirements of customers and cause internal and external rework. Costs spent on color control cannot be reduced. Color problems cause manpower, materials, and time. There is a lot of waste and loss. Therefore, how to establish a color management system that meets the conditions of the company, control the colors, and print out original documents that are both original and superior to manuscripts. The quality products that can exceed customer expectations are topics that people are most concerned about.

With the ever-changing digital technology, the function of color management software is becoming more and more powerful. The application of digital proofing and CTP technology provides an important way for the accurate transmission and control of modern colors. However, due to the fact that the conditions of Chinese companies vary widely, some companies do not match the hardware and software of each process. The management methods are still based on backward workshop-style experience, lacking effective systemic color management and quality control methods, especially the lack of Comprehensive ability of senior management personnel and excellent operational personnel. Therefore, although the introduction of first-class and high-grade prepress and printing equipment, it still can not play its advanced nature, the quality of printing products still can not go up, color control is still unstable.

I always believe that whether the use of traditional process flow, or the application of digital workflow; whether it uses advanced CTP direct plate-making technology, or the application of the traditional Phototypesetter output technology; whether it is used for soft proofing of the screen, or the application of digital proofing; whether printed with Heidelberg, etc. Machines, or the use of digital presses, to print good products, reduce rework, improve efficiency, increase profitability is the last word.

In the long-term production practice, the author has studied and summed up a set of integrated national conditions, linked to the company's actual color management theory, techniques and methods, which can effectively control the stability of color and improve the quality, so as to achieve less investment and quick results. Received instant results.

This set of color management method is good or bad regardless of the company's conditions; whether the product is high-end boutique, mid-range products or general color newspaper, can be implemented according to the normal environment of the company's usual production operations, just configure the necessary color management software , colorimeters, densitometers, control strips and other detection tools, to the entire system to match, improve and integrate. Establish color management systems with different equipment conditions, different raw and auxiliary materials, and different product grades, with the characteristics of the company, to ensure the stability of color and improve the quality.

This set of color management guidance theory and method is: the use of traditional excellent color control theory, technology, methods and advanced ICC color management theory, technology, methods and advanced prepress image processing theory, technology, methods combined, and fully Use the limits that printing can achieve and get the best copy.

I. Traditional Excellent Color Control

In the field of color printing, the traditional excellent color control is based on color theory with density control as the core. In the closed closed loop system, the electrical extension uses standard data such as gray balance and color correction, and The color is decomposed and identified, and after the output film and the printing plate are transferred, the dot is transferred to the control of printing the best on-the-spot density and dot gain and the like, thereby realizing the reduction of the original. The method is to use color, scale, test strips, densitometers and other test tools to control. Its core is from experience management, manual control and scientific control, that is to implement the standardization, standardization, and data color control of the prepress and printing process, so that the operators can achieve the quality standards and operation data.

At present, a group of advanced enterprises have started to control the color data in prepress and printing, and have relatively perfect means of color control. They have also equipped standard light sources and have changed from experience control to instrument testing. Practice has proved that only scientific test data can tell operators accurate information and thus ensure the stability of color.

However, most enterprises in China still remain at the stage of experience control. They have not yet only used test tools and measuring instruments locally, nor have they used standard light sources, resulting in unstable quality and color deviations. To date, the transition from experience management to scientific management should be implemented as soon as possible. If color is not regulated or instrument detection and control are not used, the quality and color difference of the final printed product is unpredictable.

The author carries on the first step of the color management: First of all, it helps the enterprise to establish the standardization, standardization, and data management of the entire printing process of the enterprise.

1. Standardization work

Develop quality standards for various grades of products, standards for raw and auxiliary materials, standards for well-established equipment, standards for measurement tools, and standards for ambient light sources, and produce standardized management documents. Everyone strictly follows the standards and continuously raises employees' awareness of standardization, and gradually forms a standardized environment and atmosphere.

2. Standardized work

The first is to make a meticulous and meticulous overall process specification before production, and to design specification, thoughtfulness and clearness for each product's objectives, personnel, processes, equipment, methods and measures, and to propose preventive measures in advance for possible problems in each process. From control results to control factors. The second is based on the customer's manuscript and design requirements, to do a good job of different types of manuscripts, printability conditions of different products, to achieve different specifications of the process, standardize the scan to restore the specification, digital manuscript color space conversion processing specification. The third is to do a good job in the specification of the linearization of the output film, the specifications of the printing or CTP outlets, the specifications of the digital proofing, and the specifications of the printing process, so that the work can be followed by regulations and procedures.

3. Data work

To be quantified within the scope of standards and specifications, each process needs to be able to summarize data that can guarantee quality in all places where data can be expressed. Measurable and repeatable values ​​obtained in practice are very valuable.

The above three are mutually reinforcing and interdependent. This is a basic management work that has to be done well. It is also the basis for improving the quality and stability of the entire system. It is also the basis and key to the adoption of advanced ICC color management. Well, not only can achieve stable, high-quality, high-efficiency production, but also can play a good role in paving the way for ICC color management, creating a stable, standard color basis for creating ICC Profile profiles for input and output devices.

In the stable and standard printing state described above, IT8 test proofs of various paper print suitability were printed. Such as 156g/m2 coated paper, sub-paper, light-coated paper, 80g/m2 offset paper, 230g/m2 gray-white paper, etc., choose the saturation, K value, the best uniformity of the ink proofs, using spectrophotometry The instrument measures each color patch, generates software through a profile file, and generates an ICC Profile characteristic file that reflects the printability of various papers.

Second, advanced ICC color management

Modern and advanced ICC color management technology is a new color control method based on the change of color space. The ICC color management system is built into the computer operating system and uses the ICC Profile feature file as the basis for color conversion. As long as any input or output device supports this format, accurate color conversion can be performed between them, making it easy and quick Complete color reproduction.

A complete color management system includes the ICC profile properties file, profile generation software, and standard inspection color patches required when creating profiles, color management models (CMMs), profile file connection spaces (PCSs), and application software interfaces. The ICC profile profile plays an important role. Therefore, profile generation software becomes the key and foundation for color management. The ICC Profile feature file includes the input device, display device, and output device profile.

The main developers of the profile generation software are Gellinger Macbeth (acquired by X-Rite, its holding company Amazys in January 2006), Heidelberg, X-Rite, and Kodak.

There are different versions of the standard detection color patches required to create the ICC profile properties file, such as the transmission original test pattern for acquiring the scanner ICC Profile property file is IT8.7/1; the reflection original is IT8.7/2. The Fujitsu, Agfa, and Monaco IT8 maps have 288 color patches, while the Kodak version of the IT8 map includes 255 color patches and has a portrait on the right side.

Get the digital proofing ICC Profile characteristic file test chart IT8.7/3 color marking document (928 color patches), IT8.7/4 color marking document (1617 color patches) or ECI2002V color marking document (1485 color patches ).

The second step of the author's color management: According to the specific conditions of each company, adopt phased, sub-projects to gradually achieve ICC color management.

1. Make digital proofing color management

At present, the color management technology is best applied in the digital proofing system, and has the most practical value. The color management software is also the most perfect and mature. The resident offices of the author use color management software such as EFI Colorproof XF, Fangzhen Photo, and GMG 4.1. These softwares are products that are continuously improved and upgraded. They can achieve many functions, wide adaptability, high efficiency and reliability, and can make the proofing results stable and accurate. The simulated printing color can reach about 95%. Digital proofing, due to its color accuracy, stability, reliability and repeatability, provides an effective technical means for controlling the quality of the entire process and sets up a bridge in every aspect. It can not only provide reliable parameter basis for front-end image processing, but also provide customers with standard proofs to confirm the quality of image processing, and provide standard proofs for printing, making printing easy to catch up.

2. Do a good job of monitor color management

The display is the window of dialogue between people and computers. It is currently the most important pre-proofing tool for image processing, and it is the most important key technology in color control. It is also the weakest link for many companies. Due to the large color difference between screen display and printing, Often misleading operators, causing many rework. Therefore, it is very important to do a good job of correcting the monitor and soft proofing the screen.

Some state-of-the-art monitors for image processing are of a better quality, using X-Rite's Monaco OPTIX XR screen correction instrument, Monaco Profile feature file creation software or Greinda's Spetrolino spectrophotometer with Profile Maker color The profile generation software performs the display calibration and ICC profile generation to ensure the monitor has the largest color gamut and the best display. And in the Photoshop screen soft proofing, so that the screen display and the printing effect is basically close. Practice has proved that: Through the color management of the display, it can be ensured that most of the intermediate tone colors are closer to the printing face.