A review of prepress issues

Summary of prepress problems (8)

film quality inspection standard

film output is actually an exposure process similar to photography. It first converts the dot matrix image (i.e. the picture and text composed of points) processed by rip into the signal dominating the laser, and uses the longitudinal and transverse movement of the laser relative to the film to hit (shoot) the laser point (i.e. point) to the corresponding position of the film, The corresponding part of the film is exposed, and then the unexposed part is washed out through the development and fixing process of the developer, so as to form a dot matrix image on the film

as for the quality standard of film, I think it should mainly include the following four aspects: the melt temperature can be reduced by 20 degrees

I Field density and fog, it is the basis to measure the quality of film. Fog refers to the absolute density of the blank film, that is, the density of the blank film measured after the densitometer is absolutely cleared (cleared to the air). The film with fog value = 0.03 is excellent, and the film between 0.03 and 0.07 is qualified. The so-called field density refers to the density value of large real plots. Generally, the gray scale provided by the hair and discharge software is too small. In addition, some film films have trachoma, which makes the measured value of field density smaller than the actual value, which is generally 3 8 is qualified, but if there is a large field, its density value must be guaranteed to be between 4.0-4.3 in order to ensure the color saturation of the print without merging the dark tone levels

II Linearization value, which is the main factor of film quality. Generally, it shall be ensured that the difference between the marked value on the film gray scale and the measured value is less than or equal to 2. However, because the general high-precision printing press has a certain degree of color adjustment, we can ensure the quality of printed matter as long as we ensure that its linearization difference is <= 5

III. point shape, angle and number of hanging lines. The points shall be smooth and solid without sawtooth and tail; The angle meets the standard (generally 45 degrees for monochrome and 30 degrees for four colors); The number of hanging lines is suitable for printing media (e.g. paper not higher than 120lpi, coated paper not lower than 133lpi)

IV The quality of the drug film after exposure is the last pass, and it is also the most easily ignored factor by the perfect combination of product performance and process performance. There is no trachoma on the film, no scratch on the film, no oil stain, no fixing, and no "white spots" that have not been removed. It can be said to be a film of qualified quality

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