A number of image filtering algorithms based on nonlocal means have been proposed in recent years which take advantage of the high degree of redundancy of any natural image. The block-matching with 3D transform domain collaborative filtering (BM3D) proposed in [1] achieves excellent performance in image denoising. But the choice of shrinkage operator in block-matching step is not discussed, only given the threshold by experience in its related papers. In this work, we introduce an improved version of BM3D with adaptive block-match thresholds. The proposed method firstly seeks the relationship between the Structural Similarity index (SSIM) [2] and match distance in blocks and obtains the data with fine SSIM values. Then, compute the Noise level and Gradient values in blocks of the same block size. Finally, surface fitting is adopted to get a formula which applies weak thresholds for flat blocks and strong thresholds for detail blocks. Experiment results are given to demonstrate the same class of denoising performance with less time-consuming to slightly noisy image and good improvement in denoising performance to seriously noisy image.

In this paper, we propose a new improved MC-CDMA system which combines spreading codes from Quasi-Orthogonal Matrix with Orthogonal Complex Wavelet Division Multiplexing (OCWDM). The system is implemented by complex wavelet filters which are able to lower computational complexity and increase flexibility. Novel spreading codes from Quasi-Orthogonal Matrix can be expanded randomly. It can increase user number hugely in system. Improved MC-CDMA named OCWDM-CDMA has much higher frequency spectrum efficiency and high data rate than conventional MC-CDMA. The system also has better BER performance in Gaussian channel than conventional system for much more users.

A texture synthesis algorithm based on SFLA-PSO and block increasing is presented for example-based synthesis. It can be used to speed up texture synthesizing through using the texture block of which size is increased by times of two during the process of texture synthesis; As the searching tactics of texture block matching, SFLA and PSO are combined to accelerate and improve the global searching performance. The experimental results prove that the algorithm can evidently accelerate texture synthesis on the premise of fine synthesis quality, and overcome the defect of easily falling into local optimal solution of PSO algorithm.