Multicolor printing method using rectangular dither matrices of different size, shape, and arrangement of threshold values to minimize overlap of differently colored inks at lower gradations

• US 4,809,063 A
• Filed: 05/26/1988
• Issued: 02/28/1989
• Est. Priority Date: 11/09/1983
• Status: Expired due to Term

• Current Assignee: Fuji Xerox Company Limited (Xerox Holdings Corp.)
• Original Assignee: Fuji Xerox Company Limited (Xerox Holdings Corp.)
• Inventors: Moriguchi, Haruhiko, Toshiharu, Inui
• Primary Examiner(s): Groody, James J.
• Assistant Examiner(s): NOT, DEFINED
• Application Number:
  US07/203,567
• Time in Patent Office: 278 Days
• Field of Search: 358/75, 358/75 IJ, 358/78, 358/80, 358/283, 358/298
• US Class Current: 358/535
• CPC Class Codes: H04N 1/52 Circuits or arrangements for halftone screening

Abstract

The likelihood that differently colored inks will overlap is minimized in a multicolor printing system employing the dither method by using a different dither matrix for each color and arranging the lowest threshold valued cells of the dither matrices so that they do not overlap when repeated across a printing surface. A preferred embodiment uses rectangular dither matrices of different size, shape, and arrangement of threshold values.

Claims

1. In a multi-gradation, multicolor printing method comprising the steps of generating separate color signals corresponding to a plurality of separable colors in an original image, generating a plurality of binary signals each corresponding to one of the colors by binarizing each color signal using a corresponding one of a plurality of dither patterns each comprising an arrangement of a plurality of threshold values, and performing multi-gradation, multicolor printing by recording each one of the colors using a correspondingly colored one of a plurality of inks in accordance with a corresponding one of said plurality of binary signals, the improvement comprising:

employing rectangular dither patterns which differ in size and in arrangement of said plurality of threshold values for each of said color signals so as to minimize overlapping of said plurality of inks at least at lower gradations.

2. The method according to claim 1, wherein said plurality of dither patterns also differ in shape for each of said plurality of color signals.

3. In a multi-gradation, multicolor printing method comprising the steps of generating separate color signals corresponding to a plurality of separable colors in an original image, generating a plurality of binary signals each corresponding to one of the colors by binarizing each color signal using a corresponding one of a plurality of dither patterns each comprising an arrangement of a plurality of threshold values, and performing multi-gradation, multicolor printing by recording each one of the colors using a correspondingly colored one of a plurality of inks in accordance with a corresponding one of said plurality of binary signals, the improvement comprising:

employing rectangular dither patterns which differ in shape and in arrangement of said plurality of threshold values for each of said color signals so as to minimize overlapping of said plurality of inks at least at lower gradations.