Evolution of the number of the hottest network poi

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Evolution of dots and lines

If a color ink is used in 100% amount, it can only show one depth on the printed object, which is a well-known law. However, if you use various means to decompose into different points of density on the printing plate, you can form different shades on the printed object to meet the requirements of a variety of depths. Back in the 1920s, the original lithography plate making was to use a special small steel pen tip, dip it in black ink, and manually draw dots of different depths on the lithography stone to meet the requirements. It was called the drawing tensile test high-temperature furnace: it was applied to the hydraulic universal testing machine and the electronic universal testing machine to provide high-temperature environment stone plate making for its samples. Later, the film made of different density and concave convex points was pressed, and the wooden frame (sometimes called "offset") on the surrounding shed was used as a tool, on which black ink was coated. Then, according to the requirements of different depths, it was stamped on the stone, so that the work efficiency of the large area was greatly improved due to the high elastic modulus of titanium alloy. At that time, it was about 60 lines per inch in terms of the number of lines. Photographic plate making rose in the 1930s. Glass screens imported from Japan were used to add dots to the negatives during photography, from 100 lines, 120 lines, 133 lines to 150 lines in the initial stage. Since 1965, the glass screen has been changed into magenta contact screen, and its tolerance can be adjusted with yellow filter to adapt to the density contrast of continuous color separation cathode. Then it was improved to gray contact screen with different tonality, which was produced by Beijing Institute of printing technology and Shanghai Institute of printing technology and supplied to the whole country. It is mainly used for offset printing with 150 lines. In 1973, Beijing Xinhua factory and Shanghai No. 1 printing factory first introduced German Haier dc-300a electronic color separation machine, which still adopts screen decoration. When dc-300b is to be introduced, the dot line number of gold free spraying team has accumulated rich project experience, which is slightly different, that is, 150 lines are used for version C, m and y, and 225 lines are used for version K, which is at the same angle as version y. Until the early 1980s, the electronic color separation machine was improved from analog to digital, and its number of dots and lines also developed to 175 lines, which has basically remained unchanged in the past 20 years

people in the industry know that the density of dots and lines is also called thickness, which is related to the ability of distinguishing and restoring layers, and the degree of delicacy of prints, but also to the corresponding conditions of printing. I remember that in 1959, in order to participate in the Leipzig international book and magazine Expo in East Germany, Shanghai municipal leaders put forward higher requirements for the plate making of the Shanghai Museum collection of paintings, so they made an exception and adopted 200 lines, which was carried out under the condition of overcoming many difficult conditions at that time. This also won the only gold reproduction award of the plenary session. However, the so-called "great leap forward" followed, and the national printing and plate making industry also blew a "high-line" wind that did not meet the realistic conditions of customer view. At that time, they competed to make small samples, from 300 lines, 500 lines and even 800 lines, which was called the "satellite release" in the printing industry, and beat gongs and drums to report the good news to the superiors. The production process is to shoot the 150 line screen into a 30 inch high Yang, use it to reduce to 7.5 inch Yin, and then copy it into a Yang, so it becomes the original version of 600 line points. But at that time, the zinc skin printing plate was made of the finest steel, and it was found that the precursor sand was not fine enough, so it was mixed with pumice powder for grinding, barely making a rough sample, which could not be used in machine printing at all, completely contrary to the scientific law of objective reality. I have also been involved in it, both ignorant and blindly obedient, just fooling myself and others

up to now, in the period of computer plate making, although the vast majority still use 175 lines, the scanning color splitter (or electric unit scanning system) combined with 3600 DPI and above internal drum laser Phototypesetter can emit 200 lines or even 300 lines, and can also emit frequency modulation (also known as sand dot, that is, the thinnest point of a single point that is the same as 300 lines, which depends on density or evacuation to form density, and there is no angle, so it will not produce moire). At present, due to high-performance photographic film, PS printing plate with high resolution, high adaptability ink, paper with superior performance, imported precision proofing machine and four-color printing machine, the number of dots and lines that can be accepted has exceeded 175 lines. Recently, we have seen that some fine albums printed in Shenzhen have adopted 200 lines, and the foreign black-and-white photos in the recent paper printed reference news also used 175 lines, so we should not be complacent, but we should be able to increase the number of dots and lines. Looking back on Shanghai, although it occasionally exists, it is not popular. The plate making process should be combined with subjective requirements and macro possibilities. Therefore, when we encounter the production of exquisite products and the manuscript is ideal, it seems that it is not necessary to use 300 lines at present, but to expand the idea to use 200 lines, which is neither rash nor conservative, so as to make the printing more exquisite. If CTP process is popularized in the future, it can be more suitable

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