相位相关技术实现离焦模糊图像运动估计

为解决离焦模糊图像的运动参数估计问题,介绍一种采用相位相关分析的图像配准技术。该方法利用傅里叶变换的平移特性,对产生平移的目标图像进行傅里叶变换,计算位移图像之间归一化互功率谱,其傅里叶逆变换对应二维脉冲函数,通过计算脉冲函数峰值坐标获取位移图像之间的亚像元级位移量。结合相位相关配准原理和线性空间不变退化模型,给出离焦成像系统点扩散函数及其光学传递函数的数学描述,侧重讨论离焦模糊对相位相关配准结果的影响,证明图像经过离焦退化后,位移图像之间归一化的互功率谱具有不变性。动态运动模糊图像最大检测误差0.339像元,标准差0.19像元。该方法具有可行性和有效性,能够满足一般要求。

Estimation of Displacement for Out-of-Focus Blurred Image Using Phase-Only Correlation

For solving the problem of displacement estimation for out-of-focus blurred images,the method of image registration based on phase-only correlation is introduced.The method is based on the translation characteristics of Fourier transform to search translation between images,the inverse Fourier transform of the normalized cross power spectrum of pairs images is a two dimension impulse function,and the translation displacement between images can be finely retrieved from the location of the correlation peak.The method of image registration of phase-only correlation combined with degradation model of spatially variant blur,the mathematical expression of PSF and OTF for out-of-focus blur is described,and the effect of blur on registration is discussed.The relation between variance of normalized cross power spectrum and degradation of blurred images is demonstrated,which is only dependent on the displacement between images and not on the blur in image.The experimental result shows that this method can detect sub-pixel-level shift parameters accurately and efficiently,the maximum error of registration is only 0.339-pixel.It is efficient and satisfies the system requirements.