The development of digital copying

With the development of computer-to-plate (CTP) technology in recent years, the industry generally believes that this technology will inevitably replace the existing filmmaking process, but its development has been hampered. Because the use of film processing process can still provide a certain degree of flexibility for manual modification, such as typos or local version and so on. However, direct platemaking is a one-step process that uses the platemaking machine to directly image the plate material. The data of all the images cannot be lost or lost. Otherwise, the entire page layout needs to be re-exported. In other words, compared to CtFilm, CtPlate requires a more reliable digital workflow to properly handle the production process from designer to printer. Therefore, the most controversial issue is not whether it is possible to use lasers to create high-precision outlets directly on plates, but whether there is an acceptable digital workflow to replace the existing production methods. The issues that need to be considered in the entire process include: digital copying, computer imposition, production efficiency, flexibility of modification, cost, trapping and filming. Here we introduce the requirements and techniques of digital writing.

Comparing Digital Copying with Traditional Copying

When referring to the effect of digital writing, the traditional drafting is generally used as a benchmark for comparison. Although such a comparison is a matter of course, it is often very easy to omit the benefits of some of the functions provided with digital copywriting. We will divide the three major areas below, including quality, cost, and effectiveness, and try to objectively compare the differences.

Quality effect

Color simulating ability - Since the traditional drafting machine also uses ink to image, theoretically the color gamut it can express is very close to printing. In terms of digital copying, some devices can use similar color inks similar to ink components, and the performance of color gamut is also very similar to printing. However, the cost of both ink and machine is very high (general equipment is between HKD550-1.6 million, depending on the format and accuracy). Other common color printers, such as ink jet or thermal sublimation, are more plentiful in color gamut than printing ink, and the cost is very low. The key is how to use the rich color gamut to simulate the color gamut of the printing ink, which depends entirely on the color management technology of individual manufacturers.

Net Flower Simulation Capability - Traditional drafting in this area has absolute advantages. Because they use the same set of film printing and printing. For digital copying, if you want to simulate nets, you need to invest more than one million yuan to buy high-precision equipment. However, the effect of the exchange is not very consistent with the actual printing effect. For example, the accuracy of digital drafting machine is 2000/3000 dpi, and the accuracy of the image-setter is 2400/3600 dpi. The web flowers created by both are completely different. Most of the devices on the market that can simulate nets can only meet the visual requirements of customers.

Stability - Because the traditional drafting machine is to use manual pressure and adjust the pressure, so the effect is very unstable, the industry has this experience is the same set of film to take out the draft, the effect is usually not the same. Digital writing is automatic imaging and can be very stable. Of course, if the equipment quality is not good, such as the ink head is often blocked, it will also cause instability. However, the more stable equipment on the market is not hard to find.

Reliability - Traditional drafting uses a film that is consistent with printing and is highly reliable. Digital drafting can be considered on three levels in this issue: â–¡ (1) If the RIP for outputting the draft is completely different from the RIP for the final system, then the reliability is low; (2) The RIP and the output of the draft The same as the build system, but need to be reprocessed separately before imaging, so that the reliability is higher; (3) If you can use the same set of data that has been processed by RIP for proofing and plate making, the reliability is very high . Because in addition to human factors in the entire process, the most likely opportunity for operational differences is the RIP calculation. The three methods mentioned above are all available in the market and users must pay special attention.

Cost effectiveness â–¡

Investment Costs - In this respect, traditional drafting is far inferior to digital drafting. Because of the same production capacity, such as the completion of two sets of four-color printing in one hour, the investment in traditional equipment requires four sets of drafting machines, supporting printing and processing equipment, plus the required work. With staff and a large factory building, the investment amount is about 2.2 million Hong Kong dollars. The investment in digital writing can be 330,000-1.65 million Hong Kong dollars, depending on the requirements of quality, while the additional labor is close to zero. In terms of material costs, the cost of paper and ink for traditional drafting is very low, and the higher proportion of fees is for plates and syrups. For digital copying, an open format is around HK$22-165, depending on the individual printer. In general, the return on investment in digital writing (at a certain level of quality recognition) can be much higher than traditional writing.

Performance

Production speed - The speed of image creation on the surface is faster, and printers on the market can complete a high-quality half-page layout within 20 minutes. However, traditional drafting, regardless of its size, does not include the time for imposition, printing, and stencil printing. The operation of a single draft is generally 30-40 minutes, but this is only a comparison of the production of a draft. When it is necessary to produce more than one color draft, the difference in speed between the two is closer.

A variety of simulation capabilities - Most of the above-mentioned digital printers can express more color gamut than printing inks. The rich color gamut coupled with the cooperation of good color management software enables digital copying not only to simulate the effects of prints, but also to simulate other production effects such as screen printing, digital printing, inkjet posters, etc. Simulating the performance under high-speed rotary presses can better meet the increasingly diversified output needs of the market. The most common example is a set of advertising designs that need to be promoted through different media.

Multiple Formatting Capabilities - In addition to simulating the color effects of an output medium, the full-format digital copying system can automatically adjust the color of the images in the file in response to the needs of different outputs so that the operator does not need to make manual changes. , truly automated workflow. The features of the above two digital writings are all lacking in traditional drafting.

Digital drafting options

Digital copying can basically be divided into three categories

Design proof design drafting, only for layout design.

Color proof coloring for color effects.

Screen proof proofing, at the same time for the color and net effect.

Overall, Color proof is the most comprehensive use of color drafting, with high selectivity, and can achieve the best cost-effectiveness. (figure 1)

In fact, there are many types of color printers available on the market. Their main imaging technologies include â–¡laser laser printing, thermal wax transfer, thermal sublimation, and inkjet printing. The inkjet type can be regarded as a mainstream medium-to-high end product. The following is a training material from the Rochester Institute of Technology in the United States in 1998.

Digital Printing Hardware Introduction

Heat Transfer Technology â–¡ This technology contains a wax block of pigment and is transferred to special paper. However, the color space covered by this technology is different from that of traditional offset printing. Printed manuscripts that use thermal transfer technology have a rough appearance, and the dots generated are not consistent with the printed halftone dots. The equipment investment is about 8,000 US dollars, and the cost for printing is about 3 US dollars each time.

Sublimation Technology â–¡ The Sublimation Technology Sublimation System utilizes a printhead containing thousands of heating elements and a ribbon containing CMYK pigments for texturing. The print head produces 256 different levels of heat, allowing the solid pigment to sublimate into vapor and condense on the receiving medium. In the center of each point, the color is darker and the edges are lighter. When the four printing colors are printed, the four colors are fused together into a continuous tone image. The average set of such equipment is about $25,000, and the cost per print is about $7.

Ink Jet Technology (Professional) â–¡ Ink Jet Proofing System Sprays ink onto paper to form images. Although paper costs are lower than thermal sublimation, the overall system is more expensive and requires more maintenance. The price is between $44,500 - $69,000. Each printing fee is about 2-3 USD.

Laser Technology â–¡ This technology has high precision and can produce halftone dots. The specific technologies used are different. The system accuracy reaches 1800dpi to 4000dpi. The equipment costs about 200,000 - 275,000 USD. Each copying system costs approximately US$15.

The appropriate printers only provide hardware features, and the more critical part of the complete drafting system is the part of the color management software. In the topic of digital writing, a noun is often called "ICC PROFILE". This is actually a data file with a standard format used to record the unique color gamut of different color output devices. The application of this "ICC PROFILE" in the digital copying system is just a common procedure. What users need to master most is how effective this data is produced. Is it permissible for users to perform periodic inspections? This depends entirely on the software features of individual manufacturers. The following technical description briefly introduces how Agfa can use unique concepts so that different grades of printers can perform their best color simulation capabilities.

Software introduction

Our perception of nature's color is determined by the following three factors - the type of light source, how the object changes the reflected or transmitted light, and the sensitivity of our eyes to the changed light. The eye is one of the most important sensory organs. The principle of eye color is consistent with the principle of additive color mixing. When the red, green, and blue light in the external light stimulates the corresponding cone cells, the nerves generate electrical impulses, and the nerves are excited and transmitted to the visual center on the cerebral cortex, forming a certain color, and different colors. Different visual effects. The same color has different visual effects under different contrasting changes. This is because the color contrast in the same picture will affect the brain's judgment of color. This is one of the important principles used in our color conversion. (Figures 2a, 2b, 2c)

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