JPS5757082A - Conversion method for picture element density - Google Patents

Abstract

PURPOSE:To reduce the ruggedness of a picture surface and to eliminate the blur of narrow lines to make the picture high-quality, by converting the density of only the density boundary of the picture by the boundary direction and the density of a noticed picture element. CONSTITUTION:After the picture element density quantized to 5 levels through shift register 1 and 11 is inputted to a 3X3 picture element constituting part 2, density information is given to a boundary direction operating part 3. In the operating part 3, picture element densities S2, S4, S6, S8, (S3+S7), and (S1+S9) are compared with TH (threshold for determining the picture element boundary between white and black) and SH (threshold for existence of an oblique line) and are operated as ''1'' and ''0'' signals, and a direction D of the boundary is determined and outputted to a picture element determining part 4. The determining part 4 determines output picture elements on a basis of the density S5 and the function of the direction D and outputs them in parallel. A parallel-serial converter 5 converts this parallel information to serial picture element information and outputs it.