1. A method of discriminating whether a picture is a halftone dot picture, a continuous tone picture or a line picture, said picture containing at least one discrimination unit area therein, each said at least one discrimination unit including a plurality of foreground pixel regions, each of which regions consists of any one foreground pixel and any additional foreground pixels which are immediately adjacent to the one foreground pixel or any continuously adjacent pixels in one of the major directions, said method comprising the steps of: a. binary-coding the picture using a predetermined number of pixels, thereby determining whether each pixel of the picture is a foreground pixel or a background pixel; b. determining the statistical variation in at least one of the following: (1) the number of foreground pixels constituting foreground pixel regions within a discrimination unit area; and (2) the distance between said foreground pixel regions within a discrimination unit area; c. determining whether or not said discrimination unit area is part of a halftone dot picture from a known relation between said variation and whether said picture is a halftone dot picture; and d. if it is determined that the picture is not a half-tone dot picture, then determining from a ratio of background pixels to foreground pixels whether or not said discrimination unit area is of a line picture, according to a known relationship.