US 4,557,596 A · Method of screening half-tone picture themes

Abstract

A method of screening half-tone picture themes, in which the gray tones of the half-tone picture theme are reproduced by changes in the structural width of a basic screen structure having any desired form. The assignment of a gray tone area of the half-tone picture theme to the screen structure width reproducing this gray tone area may be selectively determined. In a photographic version of the inventive method (FIG. 1), a basic screen structure 1 of any form is prepared and used to produce broadening screen structures as negative films 9,11. The same number of tone separations 20,22 is produced as negative films from the picture theme 13 to be screened, each of which tone separations reproduces a certain gray tone area of the half-tone picture theme which can be adjusted by the exposure time. Tone separations 22,20 are consecutively exposed onto a line material 24 with the broadening screen structures 9,11 respectively assigned to them, the line material then reproducing the screened picture theme in such a way that the gray tone parts determined by the tone separation are reproduced locally by the screen structure width assigned to it. There are several photographic and EDP/scanner/laser variants of this method suitable for screening half-tone picture themes, producing screened printing originals and printing data carriers with this kind of screened picture theme.

Claims23

Dependent claims

A method of screening half-tone picture themes, the various half-tones or gray tones of the picture theme being reproduced by greater or smaller changes in the structural width of a basic screen structure, characterized in that

(a) a freely selectable change, which is characteristic for the relevant gray tone, in the structural width of a basic screen structure having any desired form is assigned to each or only some of the gray tones of the half-tone picture theme,
(b) for each gray tone selected under (a), the parts of the half-tone picture theme showing this gray tone are translated into the change in the structural width. of the basic screen structure assigned to this gray tone, by overlaying the relevant parts of the half-tone picture theme singly or collectively on the changed structural widths of the basic screen structure, which may also be present singly or collectively.

Dependencies are inferred from the claim text.

Method of screening half-tone picture themes

Life of this patent

Method of screening half-tone picture themes

Life of this patent

Abstract

Claims23