Talking about the Color Management of the Color Newspaper Production Center

We often say that the essence of color printing is color decomposition and reduction. Among them, platemaking is the process of color decomposition, and printing is the process of color reproduction. Both rely on each other. The printing link stabilizes printability and process specifications and provides stable conditions for platemaking. Platemaking correctly decomposes colors to provide the correct basis for color reproduction, and color reproduction can proceed smoothly. Color management is to complete the tone reproduction, gray balance and color correction according to paper, ink and other printing conditions. For the characteristics of newspaper production, color management in color production has its own characteristics.


1 Select the original and layout suitable for newspaper printing


The characteristics of newspaper printing are: low whiteness, coarse particles, large amount of ink absorption, fast printing speed, and high dot gain rate. Therefore, the tone of reproduction is short and the color is not bright, that is, the printability is not good. In view of this, we should communicate more with the editors. We should try to use originals with medium and high-profile, bright and vivid colors, without affecting the content. Layout design should also be based on this feature, as simple and generous as possible.


2 determine the input and output device parameters


Nowadays, newspaper makers mostly use flatbed scanners as input devices. Its operation is simple, fast, and easy to grasp. However, the image quality is general and it is very suitable for newspaper production. The flatbed scanner should do a white balance every once in a while to ensure that it correctly identifies the colors. For scanners that use a long time, attention should be paid to the color shift caused by the aging of the lamp. Replace them as soon as they are found. Always ensure the scanner is clean. As an output device image-setter, the exposure intensity suitable for printing should be determined according to the characteristics of the photographic film, and the image-setter that uses for a long time should pay attention to the aging degree of the laser tube and adjust the exposure intensity at any time. The linearization of the film is to ensure that the front-end data of the plate-making is faithfully reproduced on the film, and the factors that affect it are mainly the changes of the properties of the photosensitive material and the flushing conditions. Under the condition that the photosensitive material and the developer liquid are fixed, the data that meets the requirements are tested, determined, and periodically tested in subsequent work, and the original data is adjusted in time.


3 Determine the gray balance parameters


Gray balance means that theoretically CMY can absorb GRB three-color light, and when they are equal, RGB is absorbed in equal amounts and the color appears neutral grey. However, due to the ink's error, the color of the CMY equivalent blend is color cast. Only the proper ratio of the CMY blend can display neutral gray. Gray balance is the basis of color, with ash, only with color. The color separation algorithm starts with the gray balance. Each unit has different printability at the back end, and the gray balance parameters are also different. It is the key to copying the gray balance parameters that are suitable for your own unit through specific tests. Let's talk about how to determine the gray balance parameters. First create a 21-level grayscale ladder in Photoshop, send the gray stone to the film, send it to the post-process for routine proofing, if the sample is very light after the color cast (in actual printing can not be completely colorless), explain The CMY ratio is suitable for the post process. On the other hand, adjust the CMY ratio to adapt it to the process. Specifically, adjust the Color Settings menu and the Printing inks setup menu in Photoshop. The former determines the correspondence between RGB and CMYK, that is, the ratio of CMY, and the latter changes the ratio of the selected ink. In general, the color printing separation type: GCR, black generation curve: Heavy (long tone black edition), the maximum black print can reach more than 85%, the maximum ink amount is 240% -270%, dot gain rate is 30% .


4 tone reproduction and color separation


Good print must have a rich hierarchy. Newspaper printing reflects fewer layers. How to reproduce rich layers within a limited tone is the key to our processing. According to the characteristics of newspaper printing, image processing should retain more medium and high-profile, darker compression, and greater contrast. The rejected tone should be abandoned and must not be exhaustive. The color that people see comes from the object's reflection of light. So people's perception of color depends on the light of the environment, the absorption and reflection properties of the object, and the eyes of the sensator. So it is both an optical phenomenon and a subjective phenomenon. For light, people have defined the RGB color space, and all colors are made up of different proportions of CMYK inks. Due to the limitations of CMYK inks, the color range it can express is much smaller than that of RGB color space. So color separation is actually the conversion of RGB color space content to CMYK color space. And in this big to small conversion, a reasonable choice. Reproduces the most sensitive color of the human eye. For normal manuscripts, as long as the above parameters are set correctly, the copy effect will be normal. For the color-originated manuscript, it will take some effort. The key is to distinguish between primary and secondary times, and to take care of the color of the subject so that it can meet people's visual traditions. For example, a manuscript should focus on the color of a person's skin. It does not matter if other objects have a slight color cast. The landscape painting should pay attention to whether the colors of blue sky, white clouds and green trees are vivid. In addition, as color separation color correction personnel, the correct understanding of color is not a success, you need to observe more and more memory. A conditional unit can make a set of chromatographs. Separation color correction personnel usually look at the chromatogram, and remember the percentage of dots of some basic colors. This will increase the speed faster.


5 Dataization, Normalization, Printing and Printing


Shaiban should use the standard test strip test to ensure that 2% of the outlets are not lost, and the outlets are clear and sharp. In the printing process of the color newspapers, the network expansion rate should be controlled at 20%-30%, and the color registration should be accurate. In short, the effective use of color management in the production of color newspapers is a systematic project that requires all processes to work together. Only in this way can the most perfect color be presented to the reader.