基于小波和非局部的全变差中值先验重建算法

Total variation median prior reconstruction algorithm based on wavelet and nonlocal

针对最大后验法只能提供有限的局部先验信息,使重建图像出现阶梯状边缘伪影及过度平滑等问题,提出一种基于小波收缩和非局部的全变差(total variation,TV)中值先验重建算法。在中值先验分布重建算法的目标函数中加入降噪能力优异的TV先验,提出基于TV的中值先验(median prior,MP)重建算法;针对重建图像边缘依然不清晰且存在块状伪影的问题,利用平稳小波变换具有良好的时频局部特性和平移不变性的特点,在基于TV的MP重建算法的每次迭代中,进行小波收缩和非局部降噪,进一步优化图像。仿真结果表明,该算法可以获得高质量的图像。

Total variation median prior reconstruction algorithm based on wavelet and nonlocal was put forward to solve the prob- lems of the stepladder edge and over-smoothness of reconstructed image resulted from using maximum a posterior. The median prior reconstruction algorithm based on total variation was proposed in which the total variation prior with good ability of noise reduction was added in the objective function of the median prior distribution reconstruction algorithm. To make the edge clear and solve the problem of block artifacts of reconstruction images, concerning the stationary wavelet transform having good local time-frequency features and translation invariance, wavelet shrinkage and nonlocal noise reduction were used in each iteration of the MP reconstruction algorithm based on TV so as to optimize the image quality. The simulation results show that this recon- struction algorithm can obtain high quality images.