小波变换轮廓术中用小波脊系数幅值引导相位展开的研究

Phase Unwrapping Guided by Amplitude of Wavelet Ridge Coefficients in Wavelet Transform Profilometry

为了减少小波变换轮廓术中相位展开过程的误差传递,从小波变换的相关实质出发,提出了在小波变换轮廓术中利用以前被忽略的小波脊系数幅值作为可靠度判据指导相位展开的方法。该方法选择最大幅值的小波脊系数所在位置作为相位展开起始点,根据小波脊系数幅值的大小,确定一条由大幅值到小幅值的最优化的展开路径,最大限度减少了相位展开过程中的误差传递。由于充分利用了小波变换系数的幅值信息,最大限度减小了相位展开过程中的误差传递。计算机模拟和实验验证了基于小波脊系数幅值的相位展开方法的正确性。

In order to limit the error tranfer in wavelet transfrom profilometry, we propose an idea that the amplitude values of wavelet transform coefficients at wavelet-ridge position, which has been ignored before, can be used to guide the phase unwrapping . It means that the wrapped phase located at the pixel with highest amplitude value will be selected as the starting point of the phase unwrapping, and then the pixel with higher amplitude value will be unwrapped earlier. So the path of phase unwrapping is always along the direction from the pixel with higher amplitude value to the one with lower amplitude value. Because of making full use of the amplitude information of wavelet coefficients at wavelet-ridge position, the error transfer is limited within local minimum areas during the process of phase unwrapping .Computer simulation and experimental result verify the proposed idea.