How to get good color reproduction effect on digital printing machine? "This is a delicate balance problem," according to Mr. Doug Polarkowshi, a technical expert in UARCO's printing department. "To explain the toner problem on paper, I asked customers to recall a game that children of the older generation often play. Rub the balloon on your hair, and then stick it to the wall. This game is easier to achieve when the weather is dry than summer, and it is the same reason that the toner falls.
According to the point of view of the printing staff and the production center staff, to obtain good and stable colors from the digital printing press, you need to have the corresponding tools and experience. No one of them believes that color control and calibration can achieve a fully automated process.
"We still need to have a good eye," Mr. Marc Orchant is the printing department manager of Subia, a digital printing company. He said, "And, when we are dealing with toner, we must also consider the new color gamut."
A Chrompress user, Mr. Orchant, said that Subia utilizes the company's most stable products-for example, like high-resolution film plus high-quality sheets for this work.
Next, the technician created several test files that included colors and textures (like gems, skin tones, neutral grays, etc.) that were difficult to replicate.
Finally, after linearizing the device, they calibrated the color scale under white light.
Now, the manufacturer provides the company with many tools to help them solve this problem. Agfa now offers "second versions" of three types of Chromapress consumable materials (toner, developer and imaging drum), mentioned by Agfa's product manager. Agfa emphasized that in order to avoid the expiration of developer, they already have a routine maintenance procedure.
Moreover, the Chromapress device can perform color registration and color density adjustment through the server, and can be randomly adjusted, and the adjustment can occur on the printed parts of various colors.
The thoroughness of this kind of work hopes to get results from IBM. Mr. Chris Parker, the business manager of IBM ’s color printer products, mentioned that the company spent nearly a year testing 10 identical Xeikon printers before releasing their InfoColor 70 product. “We are doing our best Find the largest area of ​​change in the display effect between the user and the device. The results clearly show that the problems caused by calibration, printing materials, or any other changing factors are much smaller than the problems caused by the actions of the operator alone. The software may only change in the registration problem, and many operators may produce several changes, resulting in a lot of waste. "
Mr. Parker believes that this trend mainly comes from the operator ’s experience in offset printing. “In offset printing, as long as the equipment is kept on until the colors on the ladder look good, it is fine. But for digital printing machines, no That ’s right. "
Interestingly, Mr. Parker claimed that the color and press control issues in digital printing are basically the same as in offset printing. "For example, for a former offset printer, the adhesion of toner is no different from the ink-water balance in offset printing. Cylinder voltage-has a great effect on digital color reproduction, a bit like the pressure of a rubber roller. LED exposure can be compared with plate exposure, "he suggested.
IBM's long-term workflow analysis of InfoColor 70 before use has enabled Agfa to include fully automatic density measurement technology in their products. This product is also equipped with a built-in heating head (to improve humidity and temperature control) and a Gretag Density meter. The latter device is connected to the server, and as long as needed, it can prompt the color value of the coding job.
Moreover, InfoColor 70 also provides: SWOP used in order to achieve automatic color matching and the color lookup table extended by European specifications.
Mr. George Willock, President of ColorStream, is very proficient in InfoColor, a digital market development company that has sold 650,000 copies of the copy program in 90 days.
Mr. Willock said that ColorStream users need user solutions for color management. Unlike the standard color tool for loading InfoColor equipment, the company (and users) use Color Partnership's OptiCal products to achieve high-quality remote and soft proofing via ISDN or T1 lines.
If color control of offset printing is a goal, then Indigo users are eager to mention that their presses (Eprint 1000+ and Omnius) do the same. “It can get the best color quality,†asserted Mr. Charlotte Krebs, Indigo Division Manager of Hollis Digital. “It ’s worth mentioning that Indigo ’s technology is unique among digital presses, and it uses liquid colorants. Electronic ink to obtain a high-gloss, offset-like effect. "
Hollis is a digital printing company with 25 employees. Mr. Krebs said that the biggest difficulty now is to match the color reproduction of early-printed or reprinted prints. The company keeps samples of all jobs to help visual matching. "Sometimes, our operators can even remember exactly how a job was printed," Mr. Krebs commented.
However, more systematically, Krebs employees formed some operating procedures: daily calibration of the device, its own color control page, and careful density measurement technology (to ensure that the device will not be over compensated).
If the color problem still exists, by outputting 3-4 proofs, "we will make adjustments on the press". If this does not work, Mr. Krebs said that they will go back to PhotoShop to adjust the files. Rarely is a mechanical problem, at this time it is best to leave it to the printing staff to solve, he suggested.
With the output of Xeikon-based equipment, if it is not maintained properly, the developer may fail, just like the plate wear during the production process of Indiog (voltage will cause a decline). Mr. Mike Chiricuzio, a long-time user of E-Print 1000 and the general manager of Sequel Inc., said that he is happy to have a new upgrade in his front-end software, which can synchronize the life of the printing plate and automatically perform change calibration.
In addition, for Sequel's more than 700 customers, the Indigo system can store density settings for each job to ensure color stability.
For the samples processed by most digital presses, climate control is the key. Sequel (at 2% humidity) has installed a humidity regulator near the printing press and even used it in conjunction with the factory's air conditioning system.
In order to get better colors, Mr. Chiricuzio looks forward to the appearance of an updated version of the Indigo ink system-ElectroInk III. He hopes that this system will provide a more gloss-matching effect with the paper used by Sequel.
In the final analysis, digital printers did not agree on the level of color reproduction they could achieve. On the one hand, Indigo users like Mr. Krebs like to show off the copied 2point text to their customers under a magnifying glass and say, "This is not possible in toner-based printing technology."
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