The sample is the weight basis of the quality control of printed matter and the tool to communicate with the customer, which is mainly reflected in the following two aspects.

First, the sample can help users check the information contained in the document so that they can be modified in time, such as fonts, images, colors, and page Settings. Color is the most difficult to control in the proofing, because different printing materials, ink and dot increase rate will cause the change of sample color.

Second, the sample can be used as a contract between the customer and the printer. The contract sample should provide the color consistent with the final print, and the contract sample should be typed not long before the printing, so as to avoid the loss of color and distortion due to the longer placement time.

Proofing is the process between printing and printing before printing, allowing users to foresee the final print effect before printing. At present, the commonly used proofing methods in gravure printing industry mainly include soft proofing, traditional proofing and digital proofing.

1. Soft proofing

Soft proofing is realized on color display, it is undoubtedly the most convenient, the fastest, the cheapest kind of proofing method, requires the color display the precision to be high, and must be properly calibrated. The obvious weakness of soft proofing is: low resolution, only 72dpi; The accuracy of color depends on the performance and calibration of the monitor; Cannot provide reference hard copy for the subsequent printing process.

2. The traditional proofing

There are two kinds of commonly used traditional gravure proofing methods, one kind is gravure proofing, the sample color is accurate, reference is high, but this way of proofing requires grinding, electric carving, electroplating and other processes, to the machining accuracy requirement of the plate cylinder is high, the plating cost is high, the process is complex, so this way of proofing production costs are high, cycle is long, at least a day.

Another method is offset proofing, which needs to output film and print, and then finish proofing on the offset proofing machine. Although this method can reduce the production cost, because the offset printing and gravure process are different, the proofing effect is quite different, such as the lack of field density and the equality of color level. The advantages of traditional proofing include the following points.

(1) the production process of proofing and printing is relatively close.

(2) use the same raster data for proofing and printing, and the potential problems can be found through proofing, such as tortoise patterns, typography and fonts.

(3) in the case of spot color and metallic color proofing, the invisibility of trap and ink is good.

The disadvantages of traditional proofing mainly include the following points.

(1) high technology content requires professional technicians to obtain accurate samples and strong labor intensity.

(2) higher investment is required.

(3) it involves more processes, higher costs and longer processing cycles.

3. Digital proofing

Digital proofing technology is completely controlled by digitalization, which changes the complicated printing process and reduces the cost. And the stability of printing and printing quality has been greatly improved. In the gravure printing process, the digital proofing is a more suitable method for proofing.

The digital proofing technology has been very mature and can meet the requirements of gravure printing. Gravure plate-making of design elements for graphics, images, more and more with the color, it mainly depends on the color of the display color than multi-color overprint more uniform, more gorgeous, and has good stability, and used in the graphics and text part of the white color can reduce the difficulty of alignment. Therefore, it is the key to evaluate the quality of gravure digital proofing. Digital proofing technology in addition to can meet general four color proofing, in view of the support ability is becoming more and more perfect color, such as professional digital proofing system for color overprint and trap, color control, the color of transparency level transition gravure process often encounter the problems such as to provide a good solution.