基于WBCT变换的水下图像高效压缩方法  

Efficient Underwater Image Compression Method Based on WBCT

作　　者：张洋[1] 李庆忠[1] 

机构地区：[1]中国海洋大学工程学院山东省海洋工程重点实验室,山东青岛266100

出　　处：《中国海洋大学学报（自然科学版）》2017年第3期124-132,共9页Periodical of Ocean University of China

基　　金：国家高技术研究与发展计划项目(2006AA09Z237)资助~~

摘　　要：针对压缩效率和重建质量无法兼顾的问题,提出一种基于WBCT变换(Wavelet-based contourlet transform)的水下图像高效压缩算法。首先根据水下图像和人类视觉系统的特点,在WBCT变换域提出了一种改进的人眼最小可觉察失真(JND)模型,以自适应去除水下图像中的视觉冗余。然后,对重要的低频系数采用定长量化和无损压缩;而对高频系数,采用基于WBCT树结构的变精度定长量化和位置差降编码策略进行编码。实验结果表明,提出的算法不仅具有较高的压缩效率,而且能获得视觉上较为满意的解码效果,适用于水下图像在甚低比特率下的压缩传输。A key application for underwater image compression is the real-time transmission of imagery from an autonomous underwater vehicle to a surface station,e.g.,for man-in-the loop monitoring and inspection operations,through acoustic channels that have limited bandwidth.To achieve high compression efficiency while keeping visually pleasing reconstruction quality for underwater images,this paper presents an efficient underwater image compression method based on the wavelet-based contourlet transform（WBCT）.According to the characteristics of underwater images and human vision system（HVS）,an improved just noticeable distortion（JND）model is fist proposed to adaptively remove the visual redundancy of underwater images in the WBCT domain.In order to fully exploit the property of HVS,the JND-based preprocessor incorporates three modulation factors,including the contrast sensitivity,lamination adaption and contrast masking functions,respectively.For both luminance and chrominance components,the low frequency coefficients are quantized in the fixed length and encoded losslessly.For luminance channel,the high frequency coefficients are quantized by variable precision and fixed length method,and are coded by the difference reduction algorithm based on WBCT trees.The proposed scheme is compared with traditional wavelet-based encoders to assess the coding performance.The experimental results with underwater images confirm that the proposed compression algorithm provides both high coding efficiency and satisfactory reconstruction quality,which is highly desired for the transmission of underwater imagery at very low-bit rates.

关 键 词：水下图像 图像压缩 WBCT变换 JND模型 

分 类 号：TP391.41[自动化与计算机技术—计算机应用技术]