Image processing method, image processing apparatus, and program

摘要

Function approximation performed when a raster image is converted into a vector image is performed in a simple manner with high accuracy, without using feedback. When anchor points are extracted from a coordinate point sequence obtained from the raster image, and function approximation is performed on the coordinate point sequence between anchor points, an appropriate point among coordinate points defined in a unit approximation section that is partitioned by anchor points is selected, and after setting the direction of the corresponding coordinate point as a tangential direction, correction is performed such that the position of a control point obtained from a tangent line does not intersect another control point.

主权项

1. An image processing apparatus comprising a processor and a memory, wherein the processor functions as:
an anchor point setting unit configured to set a first anchor point and a second anchor point that partition a coordinate point sequence expressing a contour of an object in image data into a unit approximation section of a cubic Bezier curve; a control point candidate setting unit configured to determine a furthest point most distant from a first straight line, that passes through the first and second anchor points, in a coordinate point sequence included in the unit approximation section that is partitioned by the first and second anchor points, and to set a first control point candidate and a second control point candidate on a second straight line that is parallel to the first straight line, wherein a distance between the first straight line and the second straight line is 4/3 times a distance between the first straight line and the furthest point; and a control point decision unit configured to decide, as a limit point, a point that is on a perpendicular to the first straight line, the perpendicular passing through the furthest point, and that is at 4/3 times the distance between the first straight line and the furthest point, and to decide a first control point and a second control point based on the first control point candidate, the second control point candidate and the limit point, wherein the control point decision unit decides the limit point as the first control point if a first distance between the first control point candidate and the first anchor point exceeds a first limit distance between the limit point and the first anchor point, wherein the control point decision unit decides the first control point candidate as the first control point if the first distance does not exceed the first limit distance, wherein the control point decision unit decides the limit point as the second control point if a second distance between the second control point candidate and the second anchor point exceeds a second limit distance between the limit point and the second anchor point, and wherein the control point decision unit decides the second control point candidate as the second control point if the second distance does not exceed the second limit distance.