The continuous progress of digital printing technology. So that digital printing is more and more accepted and recognize. Some models of digital printing machine image printing quality have been very close to traditional offset printing. Digital printing in many subdivisions of the printing market. Has replaced traditional offset printing. But, people’s requirements for digital printing are also getting higher and higher proofing.
Matching with traditional printing colors, color consistency, etc. Many printing factories in China are also trying to use the advantages of digital printing to better complete the original more complex printing work. For example, to reduce printing costs, digital printing can complete book printing proofing work. They can complete small batch printing using digital printing. But these jobs, it needs to be based on the color matching of digital printing and traditional printing. Let’s talk about color management with my practical work experience and provide a brief reference.
Problems with digital printing color management
Because the color management function of the digital printing machine is not ideal in actual use. It cannot meet the color requirements of printing enterprises. So it is necessary to use third-party color management software. To complete the color matching work of traditional printing and digital printing. There are two ways to achieve color matching. One is to match the digital printing and traditional printing colors. Record the printing status of the current digital printing machine. And then adjust the machine state to the first machine state each time. The other is to calibrate the color of the digital printing machine to an acceptable range every time.
Nowadays, there are many brands of digital printing machines on the market. But only a few can really match traditional printing. When I did traditional offset printing, I encountered a variety of digital proofing drafts. And Fuji Xerox digital printing machines printed the most headache proofing draft. Although the printing quality of Fuji Xerox high-end digital printing is good. But there is still a sizeable gap compared with traditional printing.
I also tried to do Canon’s digital printing machine in a fast print shop to match the color of traditional printing. The color difference of the first few matching samples is not very safe packaging. But after doing it, the color deviation is still relatively large. Even greater than the difference at the beginning (the machine is doing color matching tests while producing). After the first matching sample is transferring out and printing again. It is found that the color of the machine has changed a lot. And the machine color correction is done, the difference is still very large. I think this is a common problem with dry powder digital printing machines. And it is difficult to guarantee color stability; Let’s take another look at HP.
Indigo’s digital printing machine. Its printing quality has been very close to traditional offset printing. The color is also very close, the color stability is the best of all digital printing machines. But to achieve the color matching with traditional printing.
Both HP Indigo digital presses and traditional offset printing have a lot of preparation to make this possible.
HP Indigo needs to do the work to do upfront when operating a digital press.
HP Indigo digital printing machine is to CMYK four colors to complete the printing work. Here, only consider the use of four colors to complete the printing situation. Very suitable for the use of PDF workflow enterprises, some customers provide CMYK color mode files, directly use on the line.
And other customers bring RGB color mode files, which encounter a color space conversion problem. Whether you are in the PS software to convert to CMYK color mode, or PS files to convert. It is necessary to have a fixed color space conversion method. Which is a basic prerequisite to ensure the color stability of the machine.
It is worth noting that a considerable number of people who complete color conversion in Photoshop software. Even the early workers of the printing house are very wrong. (Their approach: task menu bar image mode All in Print, directly select CMYK mode). We can find the correct way to do this online. And some people say that the color mode should be converted from RGB to Lab mode and then to CMYK mode to be accurate. In fact, when the Photoshop software converts the color space. The program itself is first converted to Lab-mode variable data printing and then converted. I have tried these two conversion methods. And the result is the same (customize some RGB color patches, from R:0, G:0, B:0, to R:230, G:230, B:230).
The operator of the Indigo digital printing machine needs to pay attention to:
1. Do a good job in the daily maintenance and maintenance of the machine. Especially the cleaning and maintenance of the parts that have a greater impact on the printing quality.
2. It is best to use the online density meter. That comes with the machine to automatically calibrate the color of the machine. And we do not recommend it to use an external density meter to manually calibrate the color of the machine;
3. Do as little color correction work as possible in a PIP printing cycle. I think this is the most important, especially do less of full colour.
Calibration, which has strict color requirements, especially pay attention to digital printing. Because its destructive effect on color is much greater than its calibration effect.
Color matching is done with color management software
After completing the above various preliminary preparations. We can use third-party color management software to complete the color matching work. There are many color management software on the market, limited to my contact surface. I choose two more well-known and easy-to-use GMG and CGS color management software to talk.
GMG in China’s market share paper box is the highest. The actual use effect is also very good. The use of its HP Indigo digital printing machine after color calibration. Printed out of the sample and traditional offset sample color difference AE. Coated paper is 0.80 ~ 1.10, offset paper is 0.65 ~ 0.90 flexo printing. If used in Epson’s high-end inkjet printer color correction. Its color difference AE can also be below 1.6, the similarity is very high.
CGS color management software for most domestic users is relatively unfamiliar. Its actual use effect is also very good, with its HP Indigo digital printing machine color correction. With the traditional offset printing, color difference AE beverage packaging. Coated paper is 0.90 ~ 1.35, offset paper is 0.70 ~ 1.00, in the inkjet printer color correction ability is not inferior to GMG.
Of course, the two softwares have advantages and disadvantages. The following newspaper printing. I will compare the advantages and disadvantages of these two softwares.
- 1. GMG software and printing equipment is a one-to-one correspondence.
We can only use a set of software for one printing equipment. If you have multiple digital printing equipment. You need to buy multiple sets of software (software cross-version upgrade electronic supervision code later; the cost is also very high). For the pursuit of color printing enterprises, the cost is still relatively high. CGS software can realize a set of software calibration to control multiple digital printing equipment. Which is an excellent choice for printing factories with multiple proofing methods.
- 2. From the actual use effect of overprinting.
The two softwares are using circular color calibration to complete color matching. The difference is that GMG is through 4~6 times of circular color correction. To complete digital printing and traditional printing color matching. And then each time of color calibration work only 1 ~ 2 times to complete Shanghai Hongjing. CGS software to do color calibration. Each color calibration work needs 3 times of circular color correction to complete color matching. After calibrating the digital printing machine with the two software. Printing the same sheet, compared with dairy packaging. The highlight area of GMG is closer to traditional printing. CGS is more accurate in the color of the dark area. For color calibration, when it is necessary to change the part. The CGS modification is more detailed.
- 3. From the perspective of software operability.
The digital printing machine, GMG software operation interface is simple. It is easy to get started with the intermediate transition file format. The CGS operation interface is complex. The intermediate transition file format is multi-packaged. And it is not easy to get started. Besides, CGS software realizes remote digital proofing in the genuine sense. Which is a good choice for enterprises with this need. After doing a good job of color matching between digital printing and traditional printing. What printing companies need to do is to ensure the stability of the printing state. Each printing equipment, UV printing, and the printing consumables are the best fixed brands. So as not to affect the output color of the printing machine.