JPS5630366A - Picture coding method - Google Patents

Abstract

PURPOSE:To obtain a picture of high quality by effective compression by representing the density level of each picture element by a ternary value including half tone and by performing specific coding of every area, line by line, according to a fixed coding rule. CONSTITUTION:Prior to the coding of picture information, a picture-element density level is represented by a ternary value. After thickness levels of two picture elements that correspond to every two adjacent lines of picture information are summed, the white level, half-tone level and black level are denoted as 0, 1 and 2 for ternary coding. As a result, the scanning line density is reduced to half. Next, this ternary-coded picture information is coded, line by line, according to the next rule. In an area of density level o, color code 10 is assigned and the number of picture elements of it is run-length-coded. In an area of density level 1, color code 11 is assigned to every picture element, thereby performing coding. In an area of density level 2, no color code is assigned and run-length coding only is carried out. Thus coded picture signals of every line are sent to the output side.