Film quality inspection standards

The film's output is actually a photo-exposure process. It first processes the graphic image through RIP-processed dot-matrix images (that is, composed of halftone dots) and converts it into a dominant laser signal. The film is moved longitudinally and laterally, and the laser spot (ie the dot) is shot (shot) to the corresponding position of the film, so that the corresponding part of the film is exposed, and then the unfixed part is washed out by the developing process of the developing machine. A dot matrix image was formed on the film.

As for the quality standards of the film, I think the main should include the following four aspects:

A. Density and fog in the field, it is the basis for measuring film quality. Fog refers to the absolute density of the blank film, ie, the density of blank film measured after the density meter is absolutely cleared (clear to air), the film with the fog value <= 0.03 is excellent, and the 0.03 to 0.07 is qualified. The so-called field density refers to the density of the Dashen block. Generally, the gray scale of the emission software is too small due to its small area, and some film films have trachoma, making the actual density measurement value smaller than the actual value. Generally, it is qualified between 3.5-3.8, but if there is a large field, it must ensure that its density value is between 4.0-4.3 to ensure the color saturation of the printed matter and does not make the darkness level gather.

Second, the linearization value, which is the main factor in the quality of the film. Generally, it should be ensured that the difference between the marked value on the film gray scale and the measured value is <=2. However, since general high-precision printers have a certain degree of color adjustment, we only need to ensure that the linearized difference <= 5 can guarantee the quality of prints.

Third, the dot shape, the angle of the net and the number of hanging nets, the outlets are required to be sleek, full, no jagged, no trailing; the net angle is in line with the standard (usually 45 degrees for single color, 30 degrees for four colors), not hitting the net; Suitable for print media (eg newsprint no more than 120 LPI, coated paper no less than 133 LPI).

4. The quality of the film after exposure is the last measure, and it is also the most easily overlooked factor. There was no trachoma on the film in the field, no scratches on the film, no traces of oil, and no "white spots" that were not removed by the fixing. Can be said to be a quality film.