关键词: 图像消噪, 双密度双树复小波, 双变量萎缩函数, 局部方差估计

Abstract: In order to keep more details while denoising, an efficient local adaptive image denoising algorithm based on the Double-density Dualtree Complex Wavelet Transform (DD DT CWT) was proposed. The principles and characteristics of the DD DT CWT were analyzed and a Bivariate Shrinkage Function (BSF) was derived. The noisy image was firstly decomposed by the DD DT CWT, then according to the statistical properties of wavelet coefficients and the dependency of inter-scale with intra-scale coefficients, the wavelet coefficients were shrunk by the BSF with local variance estimation, and finally the denoised image was reconstructed by the shrunk coefficients. The experimental results prove that the proposed algorithm is efficient in noise removal and details reservation, and can improve the visual quality of the denoised image.

Key words: image denoising, Doubledensity Dual-tree Complex Wavelet Transform （DD DT CWT）, Bivariate Shrinkage Function (BSF), local variance estimation