Linearization and adjustment of the hottest film

Film linearization and its adjustment

content: first, the purpose of film linearization

the electric extension or control software sends a control signal to the servo valve imagesetter. Before getting the color separation film, the point matching relationship of each pixel can be known in advance through the display. However, after the film is exposed and developed, whether the points on the color separation sheet are the same as those displayed and whether the plate making data are correctly reproduced mainly depends on the development conditions and the characteristic curve of the photosensitive material. The purpose of film linearization is to match the developer with the electric extension or Imagesetter, so that the obtained point size is the same as the displayed point size. 2、 Adjustment of film linearization at present, the film linearization process of most electric extensions includes two steps: metering level and metering value. 1. Metering bit

load the determined film, input the optical bit of a data, and press the key to scan. Input another optical bit of data, and then scan. Repeat this several times to get a group of scanning films with different light levels. Observe with a magnifying glass to determine the correct light level value. Generally, the metering position is required when changing the eye system and line thickness. 2. Photometric value

after measuring the light level, input the number of lines, point angle and dot shape system, scan the 21 level electronic gray scale with different optical values, and display the film. Measure the density of the blackest level of each ladder with a densimeter, and take the light value of the ladder with a density of 3.8-4.0 as the actual scanning light value. 3. Linearization

measure the point area of each step of the ladder corresponding to the set light value with a densimeter, and input and store the point percentage of each step in turn according to the linear input program of the electric extension or Phototypesetter. These input numbers do not necessarily increase linearly according to the standard, but are compared with the linear ladder signal by the computer in the machine, and the automatic compensation of addition and subtraction is carried out step by step, so that the point data recorded on the film again can form an accurate linear correspondence with the image point signal number of color separation output (display)

when the film and development conditions change, or the thickness of the adding line and the dot system change, as well as the replacement of the normal recording and fine recording, and the change of the exposure light source, light value and exposure device, the output (display) of the color splitter will be affected. The accurate linear correspondence between the dot signal and the data of the film recording point, so the linearization test compensation should be made

when the output record of the color splitter or imagesetter is in a relatively stable state of linearization every 5000 times, only a rough single linearization test can be performed. When the linearization test compensation is made for the first time, or the output record is in the state of unstable linearization, the quadruple linearization test compensation should be made. 3、 Development condition development restricts the accuracy of film recording points to a great extent. How to stabilize the developing conditions is also a part of film linearization

1. developer. The concentration of developer has the greatest influence on the development ability, which obviously restricts the development curve. Therefore, it is necessary to ensure the accuracy and long-term stability of the composition, proportion and concentration of the developer. In addition, pay attention to the replenishment of liquid medicine and the working quality of circulating pump

2. development speed and temperature. Test the developer (film processor) used to obtain the best matching development temperature and development time when the developer reaches the highest development contrast coefficient. The adjustment of the two can complement each other within a certain range, but if the range of change is too large, it will affect the development curve. 3. Maintenance of the developer. (1) Clean the roller, filter and medicine sink regularly; (2) After the developer is stopped, open the cover to volatilize the acid gas of the fixing solution; (3) Use the developer according to the operating procedures. Only by strengthening the control of development conditions and the management of the developer can we ensure the accuracy and stability of the linearization between the recorded data of color separation pictures and the film

color reproduction is a process of point data setting and transmission. When we use the electric extension or phototypesetting machine version, whether the set point data can be correctly recorded on the output film depends on the linearization adjustment of the film and cannot become an accurate result. In other words, film linearization is the guarantee of correct point output and the basis of plate making digitalization

Author: printing technology, Hunan Light Industry College