Joint management of color

The process of color management is based on the consistency of color and the cooperability of all aspects of the print job production.

Fundamentally speaking, color management is the color of different work links. The color management system (CMS) is responsible for correctly transferring the colors of the originals to the display and finally to the color proofs. The human eye observes the appearance of the colors on each link to obtain a consistent feeling. This is a delicate process of color conversion. Subtle differences in the field of color means imperfections - such as the difference between the yellow and orange colors of cooked dates. The printing industry is evolving from handicraft production to scientific production, which has led to the systematicization of color. Developers of CMS are struggling to achieve open, fidelity transmission of information between themselves, their customers, and even competitors. This is a great challenge.

Calibration, Characterization For each print job, the color management process includes a set of standards for multiple devices and software, at least one device-independent standard.

However, each job starts with the calibration of the device. Since large deviations occur in the display from time to time, it is critical to use a colorimeter to determine if a color shift has occurred and in which color direction the shift occurred. It is important to maintain color consistency. . Therefore, the output device must be calibrated. Using a colorimeter, densitometer, or spectrophotometer, and a results analysis software, the printer or printer can be calibrated to match the software-specified output device.

The second aspect of color management - a description of the device's features, including the creation of corresponding profiles for the output and input devices. The International Color Consortium (International Color Consortium, ICC for short) has created a color profile file format widely used in the industry to standardize the generation of device description files.

Manufacturers and printers also emphasize the use of a successful color management workflow to maintain color consistency at every step of the entire printing process. Although there are many "official" printing standards, it is really important to ensure the stability of the print color. To do this, we must standardize the various variables affecting the printing process. These factors include film, printing plates, ink, paper, etc. .

The common reference standard ICC standard is based on the PCS (Profile Connection Space) reference space. Therefore, the ICC profile contains data converted from the device color to the PCS space, as well as data converted from the PCS space to the device color space.

Although this system has been widely accepted in the printing field, it still has some shortcomings. The definition of the PCS space is too narrow, because the reference space it defines has no content like black points and flares.

Here is the question of whether it is easy to operate. Since ICC profiles often use lookup tables to approximate the output values, these values ​​are not the correct values, they are only approximations to some degree, and each CMS system uses a different Way to take the value. The final quality of the ICC software depends on the vendor of the software, mainly because each CMS system contains complex mathematical algorithms to strictly characterize each device.

Commercial Tools U.S. Screen has sold the company's color management technology to a number of commercial printers. They stated that the [LabFit] system and [LabProof] system tools are also suitable for printing high-quality color packaging.

In fact, Screen's LabFit-CMS system and LabProof-proofing system are all bundled together on the screen's prepress and print quality management components (P2QM). LabFit simulates all variable factors in various printing environments and produces ICC profiles. LabFit Builder (Profile Generator) measures printed samples in four minutes, and the colors on the proofs are 85 color control color scales produced by the company. The Editor can fine-tune the colors and have the function of editing the ICC profile generated by Other application software.

CreoScitex's Prinergy Color Management System takes two major steps to complete the color space conversion process.

First, the refining process, in this process, separates the data input to the printing press so that the refined PDF file contains the colors required for digital management, controlling overprinting and final output of the colors. Color profiles can be added to the input file or used during refinement.

Second, color management will guide the proofing process so that the proofs accurately mimic the final output of the press.

The CreoScitex system also has the following advantages: The cycle time of the design is greatly shortened; the maximum color reproduction range; remote proofing; and multiple output, that is, can be output to the media (for example, the network) or can be output to the printing process.

In addition to a range of specific color management devices, GretagMacbeth recently introduced version 3.1 of ProfileMaker Professional Color Management Software, which accurately produces flat-screen display profiles; it also includes a new type of digital camera profile. The module.

The suite consists of five modules, each with an intuitive graphical user interface. The main application module ProfileMaker creates ICC profiles for various types of output and input device calculations. The ColorChecker DC Color Reference includes a wide range of color reproduction. MeasureTool can be used to collect, analyze and calculate all data. The Profile Editor controls brightness, contrast, saturation, and tone curves. The last part is that Batch Matcher automatically creates attachments in the output of ICC profiles.

Agfa's ColorTone and Color Tone Pro are excellent software packages designed to fit all types of prepress software. Color Tone fully handles input device profiles, while Color Tone Pro can use user-improved input and output device profiles. The product contains a library of files with a variety of basic features, with the ability to use with a variety of file formats.

For package printing, how large is the use of this technology? Many small and medium-sized printing companies are not eager to adopt the system of complex processes contained in the CMS. Supply companies expect the process of transformation in the digital age to maintain a steady pace, which will eventually allow people to gradually accept color management. Gretag Macbeth's Hofknecht predicts that as digital proofing is increasingly promoted, printers can gradually extend digital process flow to the prepress area through color management.