基于零相位滤波的聚焦形貌恢复技术

Depth from Focus Based on Zero-phase Filter

在聚焦形貌恢复技术中,为获取更好的恢复精度,提出了一种高精度的聚焦形貌恢复算法,该方法用零相位滤波器对窗口序列图像的评价函数值进行滤波,在消除干扰的同时,保持各空间数据点的位置不变。设计了基于切比雪夫Ⅱ滤波器的零相位滤波器;利用二次曲线的最小二乘拟合峰值位置作为窗口序列的聚焦位置,进一步提高了峰值定位精度;采用三次曲面对各个窗口序列的拟合峰值位置进行插值,进而得到被测物的全部深度信息。实验表明,本文方法的恢复平滑性和精度优于传统方法。

In order to achieve a better recovery precision,this paper introduces an algorithm for shape from focus based on zero-phase filer.The principles and design of this filter were explained.To filter the evaluation function of window sequence image by a zero-phase filter,it can keep the position of each dimensional data point unchanged while eliminating noise,so as to get a more accurate focusing position.The peak value position of the evaluation function is got by computing the extreme of the least square quadratic curve.At last using the cubic surface interpolation,all the depth of the measurement object is obtained.The experiment shows that the method of this paper is better than the traditional method at flatness.