How to control the color reproduction effect on a digital press
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How can I get good color reproduction on a digital press? “This is a delicate balancing issue,” said Doug Polarkowshi, a technical expert at UARCO's printing department. “In order to explain the problem of toner on paper, I let customers recall a game that older generations often play. Rub the balloon on your hair and stick it to the wall. This game is easier to achieve in the dry weather than in the summer, and the color drop is the same."
According to the opinions of the printers and the production center, to obtain good, stable colors from the digital press, it is necessary to have the corresponding tools and experience. None of them believe 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 manager at Subia, a digital printing company. He said, "And, when we are dealing with toner, we have to consider the new gamut."
A Chrompress user, Mr. Orchant said, Subia has taken advantage of the company's most stable products - for example, high-resolution film plus high-quality ones for this work.
Next, the technician created several test files that included colors and textures that were difficult to copy (like gems, skin tones, neutral grays, etc.).
Finally, after linearizing the device, they calibrate the color scale under white light.
Now, the manufacturer has provided the company with many tools to help them solve this problem. Agfa now offers a "second version" of three types of Chromapress consumables (toner, developer and imaging drum), said Agfa's product manager. Agfa emphasizes that they have a regular hold procedure to avoid expiration of the developer.
Moreover, Chromapress devices can perform color registration and color density adjustment through the server, and can be adjusted randomly, and adjustments can occur on printed components of various colors.
The thoroughness of this kind of work, I hope to get results from IBM. Mr. Chris Parker, commercial manager of IBM's color printer products, mentioned that it took nearly a year to test 10 identical Xeikon presses before releasing their InfoColor 70 products. "We try our best to operate." The largest change area is found in the display between the device and the device. The results clearly show that calibration, substrate, or any other variation causes problems that are much less problematic than those caused by only the operator's actions. The software may only change in the registration problem, and many operators may have several changes, resulting in a lot of waste."
Mr. Parker believes that this trend is mainly from the experience of the operator's offset printing. "In the offset printing, as long as the equipment is kept open until the color on the ladder looks good, it can be. But for digital printing machines, not Too good."
Interestingly, Mr. Parker claims that color and press control issues in digital printing are essentially the same as in offset printing. “For example, for a former offset printer, the adhesion of the toner is no different from the ink balance in the offset. The roller voltage – has a great influence on the digital color reproduction, a bit like the pressure of the rubber roller. On the digital press LED exposure can be compared to plate exposure," he suggested.
IBM's long-line workflow analysis prior to the use of InfoColor 70 enabled Agfa to include fully automated density measurement technology in its products. This product is also equipped with a built-in heating head (to improve humidity and temperature control) and a Gretag Densitometer. The latter device is connected to the server and can prompt for the color value of the encoded job as needed.
Moreover, the InfoColor 70 also provides: SWOP for use in automatic color matching and color lookup tables for European specification extensions.
Mr. George Willock, President of ColorStream, is very proficient in InfoColor, a digital market development company that has sold 650,000 copies of the program in 90 days.
Mr. Willock said that ColorStream users need a user solution for color management. Unlike standard color tools that load InfoColor devices, the company (and users) use Color Partnership's OptiCal products for high-quality remote proofing and soft proofing via ISDN or T1 lines.
If offset color control is a goal, Indigo users are also eager to mention that their presses (Eprint 1000+ and Omnius) do the same. “It gets the best color quality,” asserts Charlotte Krebs, Hollid Digital's Indigo division manager. “It's worth mentioning that Indigo's technology is unique in digital presses, using liquid colorants. Electronic ink to get high gloss, similar to offset printing."
Hollis is a digital printing company with 25 employees. Mr. Krebs said that the biggest difficulty now is to match the color reproduction of printed or reprinted prints. The company retained samples of all jobs to help with visual matching. “Sometimes our operators can even remember exactly how a job is printed,” Mr. Krebs commented.
More systematically, however, Krebs employees have developed operational procedures: daily calibration of the device, its own color-coded control page, and careful density measurement techniques (ensuring that the device is not over-compensated).
If the color problem still exists, output 3-4 proofs, "We will adjust on the press". If this still doesn't work, Mr. Krebs said they will go back to PhotoShop to adjust the file. Very few cases are mechanical problems, and it is best to leave it to the printer to solve it, he suggested.
With Xeikon-based device outputs, if not properly maintained, the developer may fail, just like the wear of the plates during Indiog's production process (voltages will decay). The old user of E-Print1000 and Mr. Mike Chiricuzio, general manager of Sequel Inc., said that he is pleased to have a new upgrade in his front-end software that can be synchronized to the life of the printing plate and automatically calibrated.
In addition, for more than 700 Sequel customers, the Indigo system is able to store the density settings for each job to ensure color stability.
Climate control is key to proofs processed by most digital presses. Sequel (at 2% humidity) has installed a humidity regulator near the press and even used it in the factory's air conditioning system.
For better color, Mr. Chiricuzio expects a newer version of the Indigo ink system - ElectroInk
With the advent of III, he hopes the system will provide a more matching effect on the gloss used 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 their copied 2point texts to their customers under a magnifying glass, saying, “This is not possible in toner-based printing technology.”