BRAILLE RECOGNITION SYSTEM WITH TERNARY-CODING

Light is obliquely irradiated onto the surface of a document in braille, and its reflected light is received, to obtain a first gray image. The first gray image is subjected, while being scanned in a direction corresponding to a direction parallel to the direction of light irradiation, to differentiation processing in the scanning direction, to produce a second gray image whose light and dark portions respectively produced by projected points have a particular pattern. The second gray image is subjected to such ternary-coding processing that the particular pattern of the light and dark portions respectively produced by the projected points in the second gray image is emphasized, to produce a ternary-coded image. Each of the projected points is extracted by pattern matching with respect to the ternary-coded image.