System for rendering bezier spline and method therefor

PURPOSE: To provide a high speed method and system with high memory efficiency by deciding when a certain curve decided by a pair of Bezier control points is sufficiently approximated by a certain segment by a computer, and stopping the Bezier curve to be subdivided into smaller curves. CONSTITUTION: An error function calculator 112 calculates an error vector by subtracting a constitution vector or a vector from an origin to a Bezier control point. A comparator 114 decides whether or not the size of a certain error function, a certain error vector, or a certain error component is less than a test size 106. When all the error sizes are less than the test size 106, a segment drawn between the Bezier end points is used for approximating the Bezier curve. When the comparator 114 indicates that any one of the error sizes is larger than the test size 106, the curve is subdivided into two parts.