Sample proofs are the weight basis of the quality control of the printed matter and the tools for communication and communication with the customer. Its role is mainly reflected in the following two aspects.
First, proofs can help users check the various information contained in the document for timely modification such as fonts, images, colors, and page settings. Color is the most difficult to control in proofing, because different substrates, inks, and dot gains can cause changes in proof color.
Second, proofs can be used as contracts between customers and printers. The same sheet should accurately provide the color consistent with the final printed product, and the same sheet is best printed out shortly before printing so as to avoid discoloration and distortion of the proof sheet due to a longer storage time.
Proofing is the link between prepress production and printing, allowing users to anticipate the final print results before printing. At present, the proofing methods commonly used in the gravure printing industry include soft proofing, traditional proofing and digital proofing.
1. Soft proofing
Soft proofing is implemented on a color display and is undoubtedly the most convenient, fastest, and cheapest method of proofing. It requires a color monitor with high accuracy and must be correctly calibrated. The obvious disadvantages of the soft proofing method are: low resolution, only 72 dpi; the accuracy of the color depends on the performance and calibration of the display; it can not provide a reference to the hard copy of the printing process.
2. Traditional proofing
There are two kinds of traditional gravure proofing methods commonly used, one is gravure proofing, and the proofs obtained are accurate in color and high in reference. However, this proofing method requires grinding, electric carving, electroplating, and other processes to process the precision of the plate cylinder. The requirements are high, the cost of electroplating is high, and the process is complicated. Therefore, the production cost of this kind of proofing method is high and the cycle is relatively long, at least one day.
Another method is offset proofing, which requires the output of the film and the printing plate, and then complete the proofing on the offset proofing machine. Although this method can reduce a part of the production cost, due to the difference between the offset printing and the gravure printing process, there are great differences in the proofing effect. The actual density is insufficient and the color levels are equal. The advantages of traditional proofing mainly include the following points.
(1) The production process of proofing and printing is relatively close.
(2) Proofing and printing use the same rasterization data. Proofs can identify potential problems such as moire, typography, and fonts.
(3) Good performance in trapping and ink opacity when spot color and metallic colors are used for proofing.
The disadvantages of traditional proofing mainly include the following points.
(1) High technical content requires professional technicians to obtain accurate proofs and labor intensity.
(2) Requires higher investment.
(3) There are many processes involved, the cost is high, and the processing cycle is long.