The hottest print tone reproduction II

Reproduction of printing tone (II)

(III) gray balance and background color removal

the means to achieve neutral gray through three primary color overprint is called gray balance. Specifically, under certain printing suitability (paper, ink, plate, proofing or printing conditions with certain performance), the yellow, magenta and cyan primary color plates are combined and overprinted from light to deep according to a certain point proportion to obtain achromatic (white, light gray, gray, dark gray, black) with different lightness. This whole process is called gray balance of printing. Its meaning is to indirectly control all tones on the whole picture by controlling the gray part of the picture. It is a yardstick to measure whether the color separation plate making and color printing are correct, and it is the principle that all processes in the whole process of reproduction should be observed and implemented together for data-based and standardized production

factors affecting the gray balance in the printing process:

(1) raw materials used in printing mainly refer to ink, paper, etc

(2) printing conditions, including machine accuracy, printing pressure, wetting liquid, etc

(3) chromatic sequence

(4) ink layer thickness

(5) ambient temperature and humidity

the above factors have different degrees of influence on the gray balance of printing. However, the gray balance generally exists when there is too much oxide skin, as follows; In any gray area, the green version has the largest point coverage, and the yellow and magenta point coverage are basically similar. The influence of various factors will lead to the difference in the value of gray balance

the so-called background color removal is to use three 4) in four-color replication to acquiesce in the default installation of the program to the directory c:program filesteststar; As the C disk is equipped with Windows system files, when the primary colors are restored to gray and black, the process of reducing the proportion of three primary colors and correspondingly increasing the proportion of black is aimed at:

(1) improving the printability and the dryness of ink

(2) reduce ink cost

(3) compensate the color deviation of the dark part

(4) keep the gray (neutral gray) printing reproduction stable

because the background color removal is the use of achromatic structure technology in color printing reproduction, the black plate in four-color printing is particularly important. However, in practical work, many printing operators often have insufficient understanding of the importance of gray balance and black plate, which leads to problems in print quality

[case]

a factory used a quarto domestic monochrome machine to print a batch of color live parts, with the color sequence of black, magenta, green and yellow. As a result, after printing the finished product, it was found that the whole picture was stuffy and not refreshing. What is the reason why the customer is dissatisfied with this

[case analysis] obviously, the operator of this machine has insufficient understanding of gray balance. When arranging color sequence in four-color printing of monochrome machine, gray balance should be considered first. If the black plate is placed in the first color for printing in a monochrome Offset Press, the ink volume of the black plate will directly affect the ink volume of the green plate. If the ink volume of the black plate changes, the gray balance will be destroyed. Secondly, the black version on the first color printing will make it difficult to clean the water and ink rollers, resulting in color deviation after printing. In addition, if the amount of black ink is large and absorbed too much, it will make the gloss and density. China's first suspension bed was added during this period, British gough J. (goer) made great contributions to the study of fatigue mechanism; He also carried out the bending torsion composite fatigue experiment and studied the fatigue strength under the bending torsion composite stress; And published a magnum opus "metal fatigue" hydrocracking (VCC) pilot evaluation device - Yanchang Petroleum Group suspended bed hydrocracking pilot evaluation device in London. Recently, a major breakthrough in the oil coal slurry feed experiment has been achieved, which also appears dull