激光主动成像图像噪声抑制方法

针对激光主动成像图像特点及实际应用需要，提出了一种基于同态滤波与双数复值小波变换级联的图像降噪算法。首先通过同态滤波将乘性散斑噪声变换为加性噪声；然后用基于改进Q-shift滤波器的双树复值小波对含噪图像进行分解，通过Bayes自适应阈值法修正小波系数；最后再进行相应的逆变换得到去噪图像。该算法具有近似平移不变性、多方向选择性及精确重构性，采用信噪比（SNR）、峰值信噪比（PSNR）和运行时间作为算法去噪性能的评价标准进行实验。实验结果表明该算法能够有效抑制图像中的散斑噪声，计算效率高，且很好地保护了图像细节。

Denoising method of intensity image for laser active imaging system

According to the characteristics of laser active imaging and practical application,a new image denoising algorithm based on homomorphic filtering and dual tree complex wavelet transform (DTCWT) was proposed. Firstly, speckle noise was converted from multiplicative noise to additive noise by homomorphic transform. Secondly, the noise image was decomposed with the Q-shift DTCWT, then wavelet coefficients were revised by Bayes adaptive threshold method. Finally, inverse transforms were carried out and the denoised intensity image was obtained. The algorithm proposed had approximate shift- invariant, good directional selectivity and perfect reconstruction. The image signal to noise ratio (SNR), peak signal to noise ratio (PSNR) and the run time were applied to estimate the denoising effect. Experimental results show that the proposed algorithm has advanced denoising performance in laser active imaging and great efficiency in computation. Meanwhile, the detail of image is well protected.