传统的基于频域和小波域的去模糊算法所得的复原图像总是存在比较明显的边缘振铃及模糊效应,而较为有效的空域迭代优化去模糊算法速度通常比较慢。为了解决上述问题,提出了基于二步迭代阈值收缩(TWIST)与总变分(TV)约束相结合的图像去模糊算法(TWIST—TV)。首先在去模糊目标函数中加入对图像的TV正则化约束,其次在对图像小波系数的每次二步迭代之前,加入对图像的TV优化去噪约束,最后迭代获取去模糊图像。实验结果表明:相对于基于频域和小波域的模糊图像恢复算法,TWIST—TV能有效抑制边缘模糊和振铃效应,复原图像的信噪比(SNR)、峰值信噪比(PSNR)高出1—7dB,平均结构相似度指标(MSSIM)可高出0.05,相对于空域解卷积算法在保证求解精度相当的情况下具备6倍以上的速度优势。
The deblurred images obtained by traditional frequency-wavelet domain based image restoration algorithms always result in prominent boundary ringing and smoothing artifacts. And the more effective space domain based alternating restoration algorithms usually work slowly. To overcome these problems, an algorithm named TwlST-TV which combines the two-step iterative shrinkage/thresholding (TWIST) and total variation (TV) regularization were proposed. This method first introduced the TV regularization constraint on the objective function, and then applied the TV-denoising method to regularize the mid- restored image in each iteration before whose wavelet coefficients were processed by the TWIST method, and eventually obtained the deblurred image. Experimental results show that, in contrast to the frequency- wavelet domain based image restoration algorithms, TwlST-TV can effectively suppress the boundary ringing and smoothing artifacts. The restored images can achieve 1-7 dB higher values of the signal-to- noise ratio (SNR), the peak signal-to-noise ratio (PSNR) and 0.05 higher value of the mean structural similarity (MSSIM) index. Proposed method has more than 6 times the speed advantage comparied with the methods which need altemating optimization in the space domain while maintain the accuracy of the solution.