PURPOSE: To eliminate an error accompanied with the reduction of the character pattern of a full dot by performing the reduction prcessing of the contour line of the character pattern after it is vectorized.

CONSTITUTION: Even when lines AB and AC expressing the contour of the character pattern which is developed to the full dot are taken as straight lines and vector-approximation is performed by setting the lines AB and AC as the contour line, the forms of the lines are not changed. When the character pattern which is formed to a vector font is 1/3 reduced next, lines (ab) and (ac) respectively correspond to the lines AB and AC. Namely, since the lines are treated as vector in reduction processing, the contour of the character pattern is not changed even after being reduced. Thus, th character pattern having little deterioration of quality is generated.