针对已有直线模型和抛物线模型空间矩亚像素定位算法对存在拐点边缘进行定位的局限性，提出了一种基于三次Bézier曲线模型的定位算法，并利用Levenberg-Marquardt迭代法来确定三次Bézier曲线的控制顶点。仿真实验结果表明，当边缘轮廓类似存在拐点的曲线时，该模型的定位精度明显高于已有的其他模型。由于该模型只是基于理想的阶跃边缘，故对于其他类型的边缘的定位尚有待进一步研究。

To overcome the drawbacks of the models of line and parabola when there is an inflection point on the edge, a novel approach to edge locating to sub-pixel accuracy is proposed in this paper. The Levenberg-Marquardt iterative method is utilized to obtain the control points of the cubic Bézier curve. Simulation results illustrate that the determination of the edges is much more accurate than that of the existing approaches when the shape of the fitted edge is close to a cubic with an inflection point on it. The proposed model is based on an ideal step edge; therefore, it will be improved to fit other kinds of edges.