Prepress Discussion: Approaching Color Management in the Proofing Field (I)

Editor's Note: The successful implementation of color management not only requires the printing company to introduce advanced tools, but also requires users to have the ability to use and manage these companies.

Industry insiders agree that the price/performance of the current proofing technology has been significantly improved over the past. In the words of Martha Stewart: “This is a good thing.” These changes have transformed proofing from an island-like simulation process to a modern technology that can be integrated with all digital workflows. Proofing has penetrated every step of the creative, prepress, and printing process we use today.

Advances in technology have enhanced communication between people, but the successful implementation of color management not only requires the printing companies to introduce advanced tools, but also requires users to have the ability to use and manage these tools. The lack of any one aspect will lead to the inconsistency of industry standards and the failure of color management in the proofing process. Although the concept of using a unified standard to verify proofs has been recognized by most people in the United States and Europe and has been widely used, a European print customer stated: “There are 80% of When it was sent to the printing factory, it was unimaginable that it was not equipped with qualified proofs. A printing factory was actually a manufacturing factory. It used industrial processes to reproduce products that were consistent with the originals, and the printing factories and customers The only contract document is a signature proof. Just as no one will drive an uninsured car, you can't start printing before you get proofs that have been validated."

The purpose of proofing

In a particular production environment, the type of color management depends mainly on the location of the proof and how it is used in the workflow. At the creation or design stage, the computer's display can provide designers with a certain degree of proofing. Next, the file inspection or preflight software "validates" the file. Although this may not be a proof in the traditional sense, it is indeed a proof. After the user has checked whether the font in the file is correct, whether the image with high resolution is clear, and whether the page is regular, the file can be used for RIP output.

During the prepress process, staff often need to use a rough proof to quickly check the page element so that it can correct its color before sending it to the customer for inspection. Although the same sheets and initial proofs are generally produced on the same device, sometimes we can produce colors that are very close to the original on a less-prepared color printer.

In the next workflow, the staff will check the content and format of each page with content or typesetting. In this case, whether it is a color proof or a black and white laser proofing, can meet the user's requirements.

Depending on the workflow and the product, people may also use the same sheet in later programs. This proofing can be used as a contract document between the printing house and the printing customer, making clear provisions on the final color and page content of the printed matter. After printing customers can sign proofs, the printing plant can be officially put into production. In addition, the operator of the printing press also needs to use the same sheet as a reference to adjust the printing color.

Imposition proofing (formerly known as "blue line proofing") is mainly used to determine whether the proofs meet the processing requirements of the job, such as: before and after the double-sided printing register, imposition order, folding, cutting and binding Wait. Historically, imposition proofing has also been used by people to correct the copy and content in the final stage.

For some important jobs, printers or print buyers may still require the use of proofs produced on the press, and even go to the shop for on-site inspection during the print production process. For example, consumer product packaging companies may check whether the printed page matches the previous product before signing the sample.

Requirements for contract proofing

Although printing clients have a wide range of proofing options, the focus of this article is on contract proofing—which is very important for both print buyers and printers. Because this kind of proof can play a role in the contract, it also has very strict requirements for color management. Let's take a look at the specific color management requirements of this proofing system.

Color Accuracy and Repeatability: These concepts are often confusing. Accuracy refers to the degree of closeness between a particular proof and an ideal color. Think about the speedometer in your car! If it is accurate, then when it shows that your speed has reached 90 mph, you may be really speeding.

Repeatability measures the stability or consistency of something over a certain period of time. Of these two factors, repeatability is more important than accuracy. If the proofing system can't accurately print the color you want, but it always produces the same effect, then you'll slowly become accustomed to it and even predict what the proof will look like. However, if the effect of proofing cannot be repeated, or cannot be consistent, then its accuracy cannot be discussed.

Our analysis of cars reflects the importance of repeatability. Maybe you know that your tachometer is inaccurate, but it is repeatable. For example, when it shows a speed of 45 mph, you know that your actual speed has reached 55 mph. If it is the same every day, then when you drive the car on the highway, as long as the speed displayed on the speedometer does not exceed 45 mph, you will not be issued a ticket. However, if the performance of the tachometer is not stable enough, when it shows a speed of 45 mph on the next day, your actual speed may have exceeded 65 mph.

Proofing requires both accuracy and repeatability. The accuracy of proofing has still been a hot topic discussed by industry insiders. As you can see at IPA and other trade shows, well-proven proofing systems generally have higher accuracy. Some device manufacturers even claim that their proofing tolerance is within 2 DeltaEs. Despite this, when you evaluate the repeatability of a system and try to integrate it with multiple systems, the accuracy of the proofing becomes very important because each system has a certain amount of error. Imagine if you had ten proofing systems in ten places, and each system had two DeltaE errors, what a big mistake would be to add up!

Verification criteria: Having each and every sheet meet certain standards is crucial for print production. Although this concept is relatively unfamiliar to many people, it is the most basic quality control method for every print production. In the case of a car, a driver's license is a radar gun in the hands of the police. It determines whether your performance meets the requirements of the relevant standards. It may be difficult for customers and printers to determine which standard they should choose, but the verification process is indispensable for any production process.

Local and remote proofing and matching of local proofs: In a proofing environment with multiple decentralized systems, the proofing site must be stable. With the upgrading of prepress systems, the popularity of broadband networks, and the emergence of globalization, remote proofing systems have become a major magic weapon for print shops to maintain their competitive advantages.

With the strong support of software, hardware, and technical services, content providers can modify and confirm the final print content and color proofing locally through a remote proofing system without having to personally go to the printing factory. This process is very fast, it not only can save on courier fees, but also allows print buyers to modify the contents of the document at the last minute before printing. In today's market, cooperation between print clients, advertising agencies and print service providers in different places has become quite common.