Proofing contrast

The comparison here refers to the comparison between traditional proofing and digital, mainly in the following aspects:

Image reproduction performance

The reproduction performance of color images includes the gray range (also called contrast) of images (including line characters), the density or chromaticity of pure or saturated colors, gray balance, the reducibility of hierarchical curves (including bright tone, middle tone, dark tone hierarchical reproduction and dot enlargement reproduction, fine texture, etc.

No matter what kind of color management software, the data in ICC format is obtained by measuring the color blocks of the standard file to be simulated and the color blocks of the printer, and the characteristic calibration file configuration file required by the proofing process is established after calculation by the color management system software. In this way, all the page image files that need proofing (including the data of PS and TIFF format files after RIP) can be sent to the digital proofing system, and the proofing proofs that match the subsequent printing can be output. No matter what kind of paper is used for printing (such as coated paper, offset paper or newsprint, even plastic, cardboard and other substrates) and what series of ink, the digital proofing system can be simulated. If the proofing quality of different digital proofing systems is slightly different at present, it mainly reflects the performance difference of their supporting color management software.

The traditional proofing technology is different from the actual printing in speed, pressure and stamping mode. It is difficult for traditional proofing to simulate actual printing, and it is also difficult for printing to catch up with the effect of traditional proofing. In practical use, printing machine operators generally feel that it is easier to simulate digital proofing, because the color difference between digital proofing and printing in the whole color space is smaller than that of traditional proofing and printing.

resolution ratio

Because digital proofing systems usually use inkjet printing or laser printing technology, the output is usually FM dot or continuous tone structure, so as long as the output resolution is above 600dpi, the proofing sample can achieve the effect of AM dot 150lpi. Now most color printers can achieve this image resolution.

RIP, a new generation of digital proofing system, can output amplitude modulation dots which are consistent with the actual printing effect, so the printer is required to have higher resolution. At present, the output resolution of Epson inkjet printer can reach up to 2880dpi, and that of HP inkjet printer can reach up to 2400dpi. It is no problem to output the amplitude modulation point image consistent with the actual resolution. Of course, from the actual dot structure, the edge of the dot on the proof is not as clear as the actual printed dot, but this subtle difference can't be seen with the mesh. What people need is that the visual resolution of the whole image is the same as that of printing.

Traditional proofing may lead to the decline of image definition because of misregister, while digital proofing does not have the problem of misregister.

Stability and consistency

There is no doubt that the digital proofing system is directly sent to the proofing system through digital page files, and all the proofs are controlled and transmitted through digital signals before output, so no matter when they are output, even if the time is several weeks, months or even years apart, the output effect of the same electronic file is completely consistent. Of course, the premise of this stability is that the hardware performance of color printers, such as ink droplet size, ink and printer performance, are consistent.

For the traditional offset printing proofing technology, it is difficult to keep the paper, ink and PS plates stable (in fact) and the state of mechanical proofing equipment (such as the pressure of the plate table, the pressure of the paper table, the height of blanket and pad, the pressure of water roller and ink roller, etc.). ) should be kept normal, and the effect of traditional proofing is also affected by environmental conditions (temperature and humidity), ink principle, dosage and its uniformity.

Compared with traditional proofing, digital proofing is almost unaffected by environment, equipment and technology, and its stability and consistency are very ideal. Therefore, the digital proofing system is used as the network proofing equipment, that is, everyone can use the digital proofing system to output proofs.

output speed

For a long time, the output speed of digital proofing system has been the bottleneck of the popularization of this technology. After the emergence of large format and high resolution inkjet printers in the market, it takes more than 40 minutes to output a large folio (102cm×78cm)720dpi sample, which does not include RIP interpretation time. At present, many models can complete the sample output time of the same format and resolution within 5 minutes, which is much faster than the traditional proofing time (it takes about 2 hours for a monochrome proofing machine to complete the four-color large format proofing). The obvious acceleration of digital proofing speed mainly depends on the development of multi-nozzle inkjet proofing technology, fast RIP proofing and servers. Some proofing servers can control four digital proofing machines simultaneously.

Proofreading format

In the past, most general high-performance digital proofing systems were in A3 (octagonal) format. With the gradual improvement of hardware resolution and speed of inkjet printers, the increase of ink cartridge capacity, and the application of changing ink cartridges without stopping, inkjet printers with large format output emerge one after another. At present, there are digital proofing systems whose output width exceeds 1.5 meters, and models of various formats can completely simulate the effects of various printed pictures.

System cost

The traditional proofing system not only needs expensive proofing equipment (imported monochrome proofing machine is more than 654.38+00,000 yuan, and domestic proofing machine also needs about 200,000 yuan), but also needs supporting proofing room (more than 50 square meters) and air conditioning equipment. At the same time, you also need to output color separation and printing plate, and the proofing cost is very considerable. The hardware of digital proofing system only includes color printer, control computer, RIP and color management software. A set of large format (large format) digital proofing system, the current price does not exceed 1.2 million yuan. Although consumables (such as ink and special printing paper) are still expensive at present, the total cost of outputting the same format and the same number of sheets (calculated by 4 sheets) is still cheaper than traditional proofing. With the reduction of ink cost and the promotion of imitation special paper, ordinary paper will be used for surface treatment and output on inkjet printers in the future, so the cost of digital proofing system may be reduced to a very low level.

At the same time, the digital proofing system takes up very little space and does not need strict environmental conditions. Without color separation, printing, mechanical proofing and other processes, not only the total cycle of prepress design, production and proofing is greatly shortened, but also a lot of raw materials are saved, and the waste of working hours and materials caused by rework once the samples are found to be wrong after traditional proofing. Digital proofing system can output proofs immediately after the original documents are modified.

Personnel quality requirements

Traditional mechanical proofing (including printing process) needs experienced and high-quality operators, and shifts are needed when the workload is heavy, which will not only bring instability in the quality of proofing samples (human factors), but also increase production costs. Digital proofing system generally does not need a special person, as long as the production designer knows how to use the proofing control computer correctly. In addition, the digital proofing system can work 24 hours a day, which is incomparable to traditional proofing.

It can be said for sure that it has become an irreversible development trend for digital proofing to replace traditional proofing.

Compared with the table proofing type, the traditional digital proofing has poor proofing performance, large color difference, poor consistency of small proofs, slow and fast output speed, large and small proofing formats, high system cost, low personnel requirements, no special requirements, and others need color separation output.

Print matching

large area

The environment requires high direct proofing, and there is no need to print matching.

Small floor space

No special environmental requirements