1. A method of generating a binarization-use pattern for use in binarization of a multi-value image, comprising: generating a basic pattern of the binarization-use pattern through calculation; determining a lighting order of pixels forming the basic pattern; and generating based on the basic pattern a rectangular pattern that functions as the binarization-use pattern, wherein generating the basic pattern comprises specifying an angle of the binarization-use pattern; specifying the number of pixels forming the basic pattern; and generating the basic-pattern-shape through calculation based on the angle specified at specifying the angle and the number of pixels specified at specifying the number of pixels, at generating the basic-pattern-shape, tetragons are generated, each of the tetragons being formed of four points of a point A(c, 1), a point B(a+c, b+1), a point C(0, d+1), and a point D(a, b+d+1) specified with arbitrary parameters a, b, c, and d, where a, b, c, and d are integers, satisfying the number of pixels n=2(ad+bc) specified at specifying the number of pixels; from among the generated tetragons, a tetragon having an angle closest to the angle of the binarization-use pattern specified at specifying the angle is selected; and two of the selected tetragons are placed adjacently to each other to generate the basic pattern, at determining the lighting-order, the lighting order is determined so that pixels forming a first tetragon of the tetragons of the basic pattern are lit in order of increasing distance from a specific point of the first tetragon, and the lighting order is determined so that, continuously from the lighting order of the first tetragon, pixels forming a tetragon next to the first tetragon of the tetragons of the basic pattern are lit in order of decreasing distance from the specific point of the next tetragon.