The most surprising aspect of the IPA Proofing RoundUP study was that the six systems with the highest average color accuracy (an objective comparison of color accuracy with the ECI2002 target) were all inkjet devices. More importantly, none of the inkjet proofs deviates from the target document by more than two deltaEs. From most observers' perspectives, they can bring about a nearly perfect visual effect. Dr. Sharma pointed out in the IPA's latest RoundUP special report summary: "Because the test results show that the repeatability of these devices, the stability of inkjet devices and presses have reached the limit, and the number of deltaE has also reached the human eye The limits of visual resolution, so there is little room for further improvement."

However, when ink-jet equipment dealers are sharing the benefits of this new technology, a new gunman begins to challenge this recognized winner. When the Proofing RoundUP team invited experienced color experts to subjectively evaluate the visual match between proofs and printed sheets, of the five best matching proofs, four were proofed by the visual screen. Made. This new proofing method based on calibrated computer monitors has shaken the dominance of inkjet equipment that has just been established.

Almost all of the top soft proofing is made by Kodak's Matchprint Virtual Proofing System (only one exception is Creo's Synapse InSite, which is now Kodak's product, ranked fifth). In the decisive battle of this soft proofing quality, the most interesting is that all of these top systems use LCD flat panel displays (corresponding to traditional cathode ray tube displays) that are either Apple or EIZO.

There are also densitometers and colorimeters on current presses. KBA's Densitronic system can test the color density on the control strip on a facing page and compare it with the spectral and chrominance values ​​in the image.

Soft proofing debut

Leo Burnett, an industry-leading international advertising company headquartered in Chicago, has a soft spot for soft-proofing technology and wants to have a workflow that applies to the global and U.S. markets. Joe Duncan, vice president of Print Innovation and Technology at Burnett, said: "The immediacy of the Kodak Matchprint Virtual Proofing System allows us to handle business across continents."

Duncan said: “Because of the cultural differences and the differences in the way we transmit colors, it is very difficult for us to implement color matching for the print jobs that are sent to Europe for production. Matchprint Virtual can bring us A unified starting point, and can provide us with a standard reference for color expression at various stages of production.We use this system to unify the color effects we want to achieve, and they select the property description file that suits their printing conditions. Match colors."

Duncan also believes that a calibrated computer monitor can provide a more realistic substrate simulation than a film proof. Duncan said: "You don't need to print saturated colors on white paper. Just tell people what the effect of these images will be in actual printing. This system has had a huge impact on our ability to preview images, regardless of the Where the piece will be printed or how it will be printed."

For standard proofing, the virtual proofing workflow is a good choice because these paperless proofs can quickly spread between towns and continents. In this case, the work exchange between unfamiliar partners is There can be a standard to follow. This also promotes the need for an output profile, which is not limited to a specific printer or a printer, but it is based on the explicit characteristics of the ideal printing conditions. From our previous history of adopting color management—when we adjusted a large number of presses to match a slightly more stable proof—we've gone back to the workflow again, here, The proofs are once again seen as the first important point of production.

The short history of proofing

Twenty-five years ago, printing operations were free and scattered, and there was no accepted normative or standard procedure. For ordinary press operators, process control is not a familiar concept. Fundamentally, the use of densitometers is not stable. Although spectroradiometers are now common on consoles or printing presses, they were very expensive at the time and hardly anyone could afford them - except for ink manufacturers.

By using L*a*b* compensation plates, the prepress department can now pass color values ​​to the press shop.

The lack of consistency in the prepress department: The image was converted to the CMYK mode by the operator during the scan based on the simple knowledge he had just learned. People produce color proofs using a simulated photolithography process. Each of the primary color maps is exposed to UV light successively to generate separate, negative images, and then these beneficograms are then applied using ruby ​​red (paint's red paint) coating and transparent microfilm strips. After countless different kinds of film-based prepress workflows, press operators and their customers are eager to find a proof that can bring them consistent, possible results. Therefore, in addition to its inherent instability, co-opting should play such a role. It became the goal of the press operator to imitate (recover color).

Generating multiple common printer profiles is an impractical workflow. Compared with the ever-changing printing effects on printing presses, the consistent coloring materials and inherent dot gains of traditional color proofs at least give people a certain degree of repeatability and safety. Don't mind the fact that with the aging of the bulb, the exposure intensity of the printing machine will unpredictably decay. Or just setting the exposure time of the continuous tone adjustment by visual measurement, even the difference in the degree of vacuum pumping to the printing machine, may also cause changes in the printing effect - from 3M (Apple), Fuji Color-Art, and DuPont. Companies such as (Cromalin, WaterProof) and others provide markings on the edges of optical proofing materials that can help press operators get rid of chaotic conditions and print color-printed sheets that satisfy customers.

The SWOP standard (web offset proofing standard) published in 1986 is the first industry standard to constrain this illegal operation. Although SWOP was published nine years ago, the booklet published in 1986 was a version that included practical guidance on printing presses and prepress operations. Through the guidance of the standardization of these previously unregulated behaviors, the SWOP committee has enabled people to finally use the term “typical” to describe the state of the press.

Now, many years have passed, more sophisticated instruments and more extensive research have brought about a more detailed description of the interaction between ink and paper in all areas of the printing industry. Until the early 1990s, the printing industry changed dramatically: Linotype-Hell invented a method to convert the colors in the scanner to CMYK color separations. This method is based on spectral measurement data, without relying on the technical level of the operator rotating the button. When Heidelberg acquired the Linotype-Hell?s prepress company in 1997, they worked with Apple Computer to transform this color conversion workflow into an essential part of the printing process. Apple called the color management system ColorSync and created a working group ICC (International Color Consortium) that we are now familiar with to monitor its implementation.

The ICC and its member companies were rapidly promoted in the first few years of the new century. Recent developments in color measurement, management, and replication technology have led to the creation of a new generation of print copy standards in the industry. The standards in the standard feature descriptors for dot gain, density, hue and other specific values ​​were developed by the ICC Working Group after careful analysis of some of the best printing companies. Whether our proofing system is based on true and reliable halftone dot technology, or based on a new generation of high resolution inkjet printing equipment or visual “soft” proofing technology, our success in the global market is It depends on the number of industry standards implemented by the printer.

Source: Bison