1992 年 55 巻 4 号 p. 268-273
The techniques of tone reproduction have been devised for various kinds of printing plates. In 4-color process printing, the tones of the original are reproduced by dot gradations. But, there are many essential problems in plate making which are difficult to solve. For example, the difference in density between original films and prints, or the unproportional relationship between density and dot gradation.
Recently, the screen rulings are getting to finer levels such as 700 or 900, and remarkable improvements can be seen in print quality.