Gravure Plate Color Correction (I)

At present, in gravure platemaking and printing products, soft packaging bags such as food, fruit, and seeds are mostly used. Customers have strict and high quality and color requirements for such products, but most originals have color casts, lack of saturation, etc. Defects, customers want the plate-printer to adjust according to his desired color when copying. Therefore, when the color separation is scanned, the adjustment range is large, the color gamut to be processed is large, and copying is difficult.
In the intaglio color reproduction process, it is difficult to properly control and transfer colors. First of all, color is a very subjective thing. Every customer has different opinions and requirements. Therefore, the adjustment and processing of colors are often not as simple as we think. Second, due to the original color, screen color, and digital proof color. It is difficult to match the color of gravure ink proofing, and the gravure and color shift of gravure inks of the three primary colors are too large to fully configure the color desired by customers; again, many operators have a theory of packaging printing and copying. The laws of the gravure plate printing process are poorly understood, resulting in high rework rates in production and large fluctuations in quality. Therefore, it is very important to master the color correction theory, methods and methods of this kind of product.
1. Gravure transformation rule of electronic engraving color copying At present, the scanning color separation picture used for gravure printing is still based on the plain printing image. Therefore, the color of the flat picture of the scanning color separation is the same as that of the electronic engraving intaglio. The digital proofing color of the IRIS proofer that batches and scans the color separation picture is basically similar to the gray balance reproduction, and then all the color reproductions thereof will be basically similar.
The electronic engraving machine itself has no color separation function, and the computer does not make any color adjustments. Only under the control of the electrical sub-scanning data, the ratio of color color to color combination is correctly converted and faithfully transferred to the gravure cylinder.
The role of electric sculpture curve adjustment is mainly two; one is to faithfully transfer the tone level and gray balance ratio of the scanned color separation picture to the gravure cylinder; the second is to compensate the deformation of the OGP film gravure proofing, printing dot network conversion, For example, high light dots can be easily reduced due to the thinness of the ink, affecting the lack of color of light colors, and the darkening of outlets can be easily expanded, affecting the level and level of deep colors. So gravure plate color correction is mainly done during scanning color separation and image processing.
Second, the theory of copying packaging products According to the characteristics of commercial packaging products, gravure color reproduction should be reproduced with the desired color so that the original color, physical color and hope the color of the three coordinated and achieve the desired effect of replication. The method should combine the reduction of process technology with the re-creation of the desired color, so that the quality of the reproduction is better than the original color and faithful to the actual color.
1. First, based on manuscripts, do a good job in the standardization and data color management of the process technology of the gravure platemaking process, so as to accurately transfer colors, control errors in color reproduction, and ensure the reproduction of manuscripts. In terms of image scanning and color separation, one is to make a gray balance curve parameter set to ensure that the original high school gray, complex color reproduction, the second is to do a good job on the basis of the color balance of the color correction standard color proof, to ensure the original color Reproducing accurately, this is a very important basic work. Color copying is a restoration technique, no matter what process, regardless of the quality of the original, no matter how large the adjusted color gamut, the extent of adjustment, the accurate color reproduction is the fundamental of the copying technology, which is the commonality of replication technology.
2. The color of the original can be reproduced after the color separation is set by the standard color amount parameter which is based on the gray balance. Then further adjustments were made to the flaws in the original color and to the requirements put forward by the customer. Such adjustments belonged to the category of recreating in the reproduction technology. Regardless of the quality of the original, it should be based on the true color of the original physical object and be adjusted and processed according to the desired color. The book "German Plate Making General Teaching Materials" mentioned that "the manuscript is the objective basis for platemaking, and the objective basis is equal to the actual object." In other words, the objective physical color is the basis for image color processing. This kind of re-creation adjustment and management, on the one hand, is full of loyalty to the original color of the commodity, highlights the attributes of the commodity, such as apple red, banana color, etc.; on the other hand, it must satisfy the client's various demands, emphasize the commercial effect of color, Highlighting the saturation of colors, that is, the commercial effect of exaggerating physical colors, realizing the saturation of colors, that is, the exaggerated rendering of physical colors, and even exaggerating to some extent to give people a strong sense of color, so that When people see the bags, they will have the desire to purchase. This is the feature of gravure printing and copying of such products, and it is also the key to improving the quality of bags.
What is always present in actual production is that many young comrades lack proper theoretical guidance and are unclear about the basic work and the concept of re-creation of the hopelessness of process technology. The practice without theoretical guidance is blind practice. As a result, the reductive work was not done well. The color of the re-creation was not handled well. Only the extension and the scanner were used as simple input devices. All the color corrections and processing were done with the PHOTOSHOP color correction tool. Random scanning color separation, low color efficiency, and poor quality.
To sum up, only under the guidance of the correct copying theory can we do a good job in scanning color separation and color correction of images, and we can get a multiplier effect.
Third, the color processing methods and methods 1, highlighting the saturation of color Fruit, seeds and other flexible packaging products require a strong color to be made bright, so when performing color correction and processing, you should master the following methods and methods:
(1) When engraving rollers, the M color plate should be 30 degrees or 37 degrees, which is easy to ink.
(2) When the engraving is done, the net depth is a little deeper, so that the ink content increases, and the red color is drawn to meet the customer's requirements.
(3) The large field of large red, which is important in the field, can be re-engraved in order to highlight the special bright fruit with bright red color. (To be continued)