Abstract: A data carrier with at least one halftone images 10 represented by structural elements 12, whereby a predetermined symmetrical widening of structural elements 12 represents a corresponding gray level of halftone image 10. Image 10 has predetermined areas 14, 16 and 22 each having a predetermined number or screen frequency of structural elements 12, the screen frequency of structural elements 12 per unit area of area 14, 16 and 22 being different between at least two areas 14, 16 and 22 and/or structural elements 12 being offset from each other in at least two areas 14, 16 and 22. A data carrier with such a halftone image 10 acquires a moiré pattern in at least predetermined areas of halftone image 10 when copied, so that a copy of the data carrier is recognizable immediately and with the naked eye (FIG. 1).

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.

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.

Abstract: A data carrier, in particular check paper, having a picture theme printed on by the dot screen, grain screen, line-halftone combination or special screen techniques or as a line copy, which is printed over by a security pattern serving the purpose of protecting the data carrier. The picture theme is interrupted by a negative security pattern adapted to the security pattern, into which negative security pattern the security pattern is printed congruently. The lines of the negative security pattern are preferably wider than the lines of the security pattern, so that the lines of the security pattern integrated into the picture theme are at a certain distance from the lines of the negative security pattern in the entire picture area and do not touch the picture theme.

Abstract: A data carrier, in particular check paper, having a picture theme printed on by the dot screen, grain screen, line-half-tone combination or special screen techniques or as a line copy, which is printed over by a security pattern serving the purpose of protecting the data carrier. The picture theme is interrupted by a negative security pattern adapted to the security pattern, into which negative security pattern the security pattern is printed congruently. The lines of the negative security pattern are preferably wider than the lines of the security pattern, so that the lines of the security pattern integrated into the picture theme are at a certain distance from the lines of the negative security pattern in the entire picture area and do not touch the picture theme.