Method for converting a video signal into a black/white signal

US4257070A · kind A · utility

Assignee

• Dr.-Ing. Rudolf Hell GmbH, Firma · DE

Inventors

• Rudiger Sommer · Kiel, DE
• Hermann Wischer · Kiel, DE

Key dates

• Filing date: Apr 3, 1979
• Grant date: Mar 17, 1981
• Expiry date: Apr 3, 1999

Classification

• Technology area (CPC H): Electricity
• CPC primary: H04N1/40093
• WIPO field: Audio-visual technology
• WIPO sector: Electrical engineering

Abstract

A facsimile scanning method for converting a video signal, generated by opto-electronic scanning of an original copy, into a bilevel black/white signal in facsimile reproduction. In the black/white recording of colored originals in which both the background and the information can be white, black, grey or colored, white/grey (colored)/black transitions in the original are frequently not picked up correctly so that information is lost in the copy. The invention solves this problem by recording colored, grey or black areas in the original as "white" with black boundary lines, by means of suitable electronic circuits. If the colored area in the original is a background area without information content of its own but containing a black item of information (letter), the legibility of the black letter in the area is increased in the copy by reproducing the background area as "white". On the other hand, the background area remains recognizable in the copy with respect to the white of the paper by virtue of its surround. If the colored area in the original, however, is itself an item of information, e.g. a broad letter, the line-boundary according to the invention causes at least the conto…