由于水体对激光存在着吸收和散射效应,距离选通水下激光成像系统所获得的图像存在不同程度的劣化问题,具有信噪比低、边缘模糊等特点。为提高图像质量,在分析水下激光成像劣化过程的基础上,研究了水下激光图像的基本噪声特征,并结合点扩展函数和调制传递函数,利用威尔斯小角度近似理论,将盲反卷积方法应用到水下激光图像复原中。在进行盲反卷积图像复原时,比较和讨论了将原始图像和经过降噪处理后的图像分别作为初始输入的处理结果;并对当人为改变调制传递函数和点扩展函数时所得到的图像复原结果进行了研究和讨论。处理结果表明该方法能达到抑制背景噪声、突出目标细节、提高对比度的效果,对水下激光图像增强十分有效。

The degradation characteristic is one of the features of images acquired by range-gated underwater laser imaging systems for the reason of inevitable absorption and scattering by water. The underwater laser images have behaviors of low signal-to-noise ratio and blurry edge. In order to enhance the image quality, the degradation process of underwater laser imaging is analyzed. The basic noise pattern is studied, and with the partial knowledge of point spread function and modulation transfer function, the blind deconvolution approach is applied in underwater image restoration utilizing Wells small angle approximation. The results of direct processing and using denoised image as the input of blind deconvolution are compared and discussed. Moreover, the different restoration results are obtained and discussed by intentionally changing the modulation transfer function and point spread function parameters. The restoration results show that the method proposed is effective in enhancement of underwater laser imaging to restrain background noise, clear object details and advance contrast.