Standard problem of color management in digital proofing
We are a big printing company in Shenzhen China . We offer all book publications, hardcover book printing, papercover book printing, hardcover notebook, sprial book printing, saddle stiching book printing, booklet printing,packaging box, calendars, all kinds of PVC, product brochures, notes, Children's book, stickers, all kinds of special paper color printing products, game cardand so on.
For more information please visit
http://www.joyful-printing.com. ENG only
http://www.joyful-printing.net
http://www.joyful-printing.org
email: info@joyful-printing.net
The core issue of color management is to determine the true color meaning based on a known color information, such as RGB or CMYK values, and to replicate this true color perception on another device by changing the transmitted color value. Whether the color management work is effective depends on whether the device profile file used is accurate. If the device's characteristics are changed, the property file is no longer accurate, and we cannot accurately get the color we want to copy. Therefore, in order to maintain the consistency of product color in the long-term production, it is necessary to standardize the operating environment, which is also the premise of the role of color management technology.
Calibration in the three steps of color management is the basis for implementing a color management system. Calibration is the method of adjusting each device (display, scanner, proofer, etc.) to a defined standard state. The purpose of the device is to achieve consistent behavior, and the device's profile describes it correctly for proper color management. jobs.
First, the implementation of color management in digital proofing
Second, establish a standardized operating environment
Standardized operation should start from step by step. Only in accordance with standardized and standardized operation procedures, the entire digital proofing process can be relied upon to improve the quality of proofing and achieve perfect matching with printed proofs.
1. Printer specifications
The quality of digital proofing is closely related to printing software, printers, ink, and paper. Only by determining the standard parameters of various processes, the equipment can achieve a good working condition, and it is possible to achieve the stable process conditions required for color management.
1.1 experimental conditions
EPSON STYLUS 10600 color inkjet printer, EYE-ONE spectrophotometer;
Founder Changliu color management software, software profile maker5.0 that generates ICC files;
EPSON digital proofing paper, EPSON original six-color ink
1.2 experimental steps
Establishing the basic linearization of the printer, which determines the physical properties of the paper and ink, and obtains the largest possible color density with the smallest possible amount of ink, providing the basis and optimization features for the creation of printer paper ICC profile files. Thereby establishing the basis of color management.
Take the method of smooth flow as an example, that is, directly print the four-color gray scale ruler and test it with a spectrophotometer to directly generate the basic linearity of the printer. The total amount of ink is then printed, and the total amount of ink in the printer is determined from the printed sample.
After doing basic linearization, first print out the ECI2002 color standard, and test the L*a*b* of the color block with a spectrophotometer, and then generate an ICC profile file reflecting the printability through the profile maker software.
2. Specification of the printing press
Color management for digital proofing must first establish a standardized printing state. The ICC profile generated on this basis can accurately reflect the ability of equipment and printed materials to express color. The resulting digital proofing is truly practical in actual production. .
2.1 prepress process specification
The film output from the imagesetter is required to meet the quality standards of the output film. Standardization of process parameters including phototyper exposure, linearization cycle, rinse time, rinse temperature, compensation amount, solid density, and fogging. It is required that the error of each point of the film output is ±1%, the maximum density is ≥4.0, and the dot curve of the output is straight.
In addition to the factors that should be considered in the photo-discharging process, the printing process also includes adjustment of the exposure amount. The adjustment of the exposure amount is mainly determined by the gray scale, micro-line block and dot performance on the print control strip (mostly FOGRA). 3%-98% of the outlets appear to be better.
2.2 printing process specification
Printing process specifications mainly include: paper ink performance parameters, ambient temperature and humidity, plate blanket selection, printing color sequence, printing speed, printing pressure, solid density.
The L*a*b* values of the ECI2002 color patches printed in the standard state were tested using the software Profile maker and the eye-one spectrophotometer, and an ICC profile file reflecting the printability was generated.
Third, the analysis of color management applications
The ICC profile file that has been obtained before to reflect the characteristics of the printing process and the ICC profile file reflecting the characteristics of the color printer are placed in the smooth flow, and the file matching is performed by the color management module (CMM) in the smooth flow, so that the digital proofing simulation is finally completed. The effect of printing also creates an ICC profile that ultimately reflects the effect.
If you are not satisfied with the effect of the proofing system you are using, we can select a paper with a printability between the various paper characteristics and create a profile with this combination of paper/ink/printer as the target value. Once the press is characterized under these conditions and the target value of the paper/ink/printer combination is established, the proofing device can be characterized for this target value. During proofing, the color is converted from the printing machine characteristic file to the characteristic file of the proofing machine, and the dot gain is changed by the curve on the image-arranging machine or the direct plate-making machine, so that the single printing machine characteristic file can be used. Different proofing effects.
However, only one color space conversion can not accurately convert the color. According to the actual situation, the ICC file of the printer needs to be modified and edited multiple times, and the dot gain rate, gray balance data, UCR and GCR parameters of the ICC file can be modified. The total ink amount of the ink, etc., can also adjust the yellow, yellow, black, and black color curves separately. In order to ensure the consistency of the simulation effect, re-measure the data after using for a period of time, and make a new characteristic file with a slight adjustment of the black version curve. .