Current status and implementation of color management in printing enterprises
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
"Color management" is one of the hottest words in the printing industry, especially in prepress. Color management refers to the precise control and management of color transfer during the production process to achieve perfect color reproduction.
First, Analysis of the current situation of color management in printing enterprises
Nowadays, printers basically think that color management is a matter of prepress, and has little to do with the printed part. In fact, in order for the printing company to achieve true data and standardized production, it is necessary to incorporate this part of the printing into the field of color management. If only the color management of the prepress part is implemented, it does not mean much to the actual production of the printing house. The quality of printed matter is the most important thing to look at the final result of printing. If the printing ring is missing, there is no way to fundamentally guarantee the quality of the product, let alone the quality of the product.
Nowadays, many manufacturers, especially large and medium-sized printing factories, have basically implemented color management in the prepress section, but the quality of the products has not been well solved, especially in terms of color repeatability. The small factory of color management is basically no different. Whether the colors are consistent or not depends on the skill of the operator. Let us give an example to illustrate, for example, customer A produced a leaflet at the beginning of the year, and today, half a year later, he will reproduce the same leaflet. Although the film used is the same, the conditions for printing are the same, the printing machine is the same machine, the ink is the same brand of ink, but in order to make the single color of the current production consistent with the original one, they still cost The strength of the nine cattle and two tigers basically met the requirements. At this time, people can't help but ask, have they not implemented pre-press color management? Why is this happening? This is because they did not manage the color of the printed part, that is, the printing machine did not do data management, resulting in the lack of debugging standards for the printing press, and it was difficult to achieve a consistent production state. That is, the best solid density, the expansion rate of the outlets is no longer the same.
So far, many printers have thought that it is impossible or difficult to implement color management for printing. This view is obviously wrong. We can look at developed countries in Europe and America. They have implemented color management throughout the production process, and all aspects have achieved data production. The operators of their printing presses can wear suits, tie and work, and clean up the whole body. It seems that it is not impossible to implement, but the wrong view makes us not implement it at all.
Second, the implementation of color management in printing enterprises
The color management implementation process of the production process can be divided into three parts: prepress, plate making and printing, which are independent and related to each other, using the black box principle. Note: Prepress includes image processing, film output; plate making refers to the processing of the PS version, including printing, developing, etc.: as shown below:
Although the production process can be artificially divided into three parts, they are not isolated and there is an inseparable connection between them. So how is color management implemented? We know that the determination of print quality is actually a judgment of the color reproduction. Whether the color is correctly restored is ultimately reflected in the printed matter. So, are we doing this from printing? No, color management should be implemented as follows:
1. Implementation of the plate making part
Because the plate making part is very independent, there is no need to consider the prepress part and the printing part. The thing we have to do is also very simple, is to determine the printing time, development time. Professional test strips (such as Brunel test strips) can be placed on the plate, and then the test strip and plate density meter can be used to determine the optimal plate time and development time. Ensure that 3% of the outlets on the PS version are out, 97% of the outlets are not dead, and the resolution line is 0.008 mm incomplete.
2. Implementation of the prepress section
The main tasks are: correcting the display instrument; correcting the input device, such as a scanner; correcting the output system (including software and hardware), such as CTF system, CTP system.
2.1 display correction
The purpose of calibrating the display is to make the displayed image and the final output image color as close as possible. The steps of calibration are as follows: ● Preheat the display for half an hour after the display is turned on, so that the display is in a stable state; ● Adjust the indoor light source to a level that can be maintained frequently, turn off the extra light source, and set the brightness and contrast of the display; ● Turn off All desktop patterns, change the background color of the display to neutral gray, which helps to adjust the gray balance; ● Set the Gamma value, first call up the Gamma control panel, select the appropriate Target Gamma at the top of the dialog box, ie the target Gamma Value, the general image is recommended to use 1.8, if you want to use the VCR or film to record the output image, Gamma is only set to 2.2; ● Correct white field, first create a blank new file in Photoshop, then select one and print For the same whiteness paper, click the WhitePoint button and drag the triangle slider until the white in the display matches the white in the pattern as much as possible; ● Correct the Gamma value and adjust it with GammaAdjustment until it is in the two-color gray bar above the triangle slider. The two color blocks have similar visual effects, no obvious boundaries; ● Correct color balance and gray balance, click Balance Adjust the RGB tri-color slider until there is no color in the gray ladder below the slider, which is a gray level; ● Correct the black field, click "BlackPoint", drag the RGB tri-color slider until the slider below the slider The dark part of the ruler is consistent with the dark part of the gray scale in the print. After the above steps, the color correction process of the display is completed. The color correction result will immediately affect the display of the monitor. At this time, the Gamma window is closed, and the Gamma window setting will take effect each time the computer is turned on.
2.2 scanner calibration
For scanners, products from different manufacturers have their own color correction system, such as: MICROTEK's DCR (dynamiccolor rendition) dynamic color correction software, Agfa's FotoTune color management software, Tsinghua Unisplendour's ImageCalibration color management software, etc. Through these color management software, color compensation is automatically performed, and the color distortion problem of the scanned image is effectively solved, so that the color image has the best color effect. The use of scanner color management software is very simple. Take DCR as an example. First, the standard color table AGFA-IT8 (for scanning reflection) and KODAKQ-60 (for scanning transmission) provided by MICROTEK are placed in the scanner. Execute the MICROTEK CALIBRATION program, select CALIBRATE, and activate the DCR color correction system to complete the operation. When scanning a general image later, simply check to see if DCR is selected, and once selected, DCR will automatically be applied to all scanned color images.
2.3. Implementation of the printing section
To do this part of the work, you must do a lot of printing experiments for different types of paper. Adjust the printing pressure, ink volume, and water volume separately, and print twenty-level gray ladders and professional measurement and control strips (such as Brunel control strips). Density measurement is performed on the printed sheets, and the expansion ratios of the high, medium and low dots of different color plates are calculated and the relative contrast (K) under different conditions is calculated, K=(Ds-Dt)/Ds Ds refers to the density in the field, and Dt refers to the density of dots at 60% to 80%, usually 75%. According to the principle of the maximum contrast value, the optimal solid density of various types of paper, the dot enlargement rate of the high, medium and low-key, and the printing pressure are finally determined.
2.4. Realization of gray balance
The realization of gray balance is the fundamental correction of color. To achieve gray balance, it is necessary to combine prepress and printing. I have already done the data processing of the printing machine before. Now I set the printing machine according to the data, and print the twenty-level gray scales of the three-color overprinting. Of course, there are also professional measuring and control strips for control. At this time, it will be found that the gray scales printed by the three colors are not gray, but always biased toward a certain color. In this case, you cannot overprint the gray by adjusting the pressure or the amount of ink in the press. You can only adjust the parameter settings of the image processing software, such as the specifics in the Printing Ink Setup module in the Photoshop system. Parameters, by setting the dot enlargement curve for each color, and adjusting the size of the output dot to achieve gray balance until the three colors are overprinted.
2.5. Implementation of digital proofing system
After completing the above work, if the manufacturer has a digital proofing system, the implementation can be carried out. Let the printing press print out the proofs. As a debugging standard for digital proofing, the proofs also need to contain the IT8.7.3 color standard to generate the printed ICC curve for the digital proofing system to call. Once the digital proofing system has been commissioned, it is very important that no changes can be made in the normal work. Sometimes the customer will say that the color is wrong after seeing the digital sample. The operator may directly adjust the system to meet the customer's requirements. This will cause the digital proof to no longer be used as a standard proof.
Third, the conclusion
After color management implements the printing system, first of all, all the data is sorted and archived in case of emergency. Second, strengthen the awareness of data production and ensure that the production process is truly digital. Third, the device is linearized according to actual needs. Only by doing the follow-up work can we truly reflect the value of color management and fundamentally guarantee the quality of the products.