Proofing as the last step in a DTP system serves the following two roles throughout the prepress area:
1, as the basis for scanning in the prepress system, production status inspection and print specifications audit, provide customer proofs;
2. Provide the printing department with the printing operation standard. There are two proofing methods that provide proofs for the prepress system:
1 The simulation of the traditional simulation printing process;
2 Digital proofing by color inkjet printers, dye-sublimation printers, and other devices in a DTP network.
Because of the totally different raw materials used, the working methods, and the raw materials used, there are some differences in color performance and quality. Therefore, it is absolutely necessary to understand them and choose which type of proofing method to use according to actual needs.
First, the role of simulation and proofing in the DTP control method with a round flat, hand-kick proofer, using the same printing plate, paper, ink to print analog color printing, to check the quality of image scanning and Making specifications is called proofing in the prepress area. For decades, it has been used as the last process before printing in this field and has never changed. Since the entire operation requires the use of water, in order to distinguish it from other proofing methods, it is also referred to as proofing.
Simulation proofing has one of the biggest advantages in the prepress area. It uses exactly the same paper, ink, printing plate, and printing method as the printing. It simulates the entire printing process. Therefore, the final proofs obtained are easily consistent with high-volume prints.
In the production process, it also needs to output the film and print the printing plate; adjust the balance of water and ink on the proofing machine; after each color is printed, it is necessary to carry out tedious and serious cleaning of the ink roller and rubber blanket. Therefore, the time required for preparation is very long. In general, it takes 3-4 hours to complete the final proofs of the four colors. At the same time, its production cost is relatively high, A4 format is usually about 20-25 yuan. From the point of view of the speed of analog proofing, it takes much more time than the DTP's high efficiency system.
In the pre-press field, the quality control of analog proofing has always been given high priority. Because before the digital proofing application, it was the only means for the operator to verify the quality and customer's final approval, and it was also an important part of the data control in the prepress field. It will require a contrast of colors and layers...
1. Control of several main data for simulation proofing In order to ensure the stability and accuracy of the proofing quality, it is absolutely necessary to make certain working data for proofing. The main data indicators that affect the quality of proofing are as follows:
The actual field density of the proofing field reflects the condition of the paper accepting the amount of ink. When the ink is transported from the plate to the blanket and then pressed onto the paper by the blanket, part of the ink is absorbed by the fibers of the paper, and the other part of the ink forms the film surface of the ink layer on the surface of the paper. When an offset paper is used as a printing horse paper, since paper fibers are loose, its ink absorbency is large. Therefore, the amount of ink required during printing will increase, and the surface of the ink layer formed on the surface of the paper will be thinned. In addition, the surface smoothness of the offset paper is low, and therefore, even if it absorbs ink even more, the reflection density of the ink does not appear high.
Under normal circumstances, we use the ink reflection density on coated paper as the data control standard for the proof density. The optical reflection densities of the yellow, magenta, cyan, and black four-color inks are generally in the range of yellow 9-1.1, magenta 1.3-1.4, blue 1.5-1.6, and black 1.8-1.9.
The above control data should ensure that the normal outlet status is valid when proofing. In the case of an unfavorable state of the network, its actual density is meaningless. At the same time, the brand of ink used is different and its reflection density is also different. Under normal circumstances, the hue, magenta and cyan can be set to lower reflection densities when the ink has a high hue.
2, proofing network expansion value since the simulation is a simulated printing press printing state, but after all, is a round flat printing. Even if the printing pressure is not as large as the printing press when the ink is delivered, it still has a printing pressure, so that there is inevitably a dot expansion. Dot gains will vary depending on the paper. (to be continued)
Positive Ps Plate,Lithography Offset Ps Plates,Aluminium Ps Printing Plate,Free Sample Ps Plate
SUZHOU HUAGUANGBAOLI PRINTING PLATE CO.,LTD , https://www.huabaoiguang.com