低位码率移动通信中的低复杂度小波图像编码(英文)

Low complexity wavelet image coding for low bit rate mobile applications

介绍一种新的具有低复杂度的可用于实时传输的图像编码器,它使用了一种基于局域方差分析的边缘保护方法来提高被压缩图像的可视性和可识别性.这样的分析和压缩方法是通过将图像划分为多个块处理来实现的,所开发的能使边界效应最小化的提升小波滤波器组,通过提升系数的量化实现定点运算,并用位移和相加来取代乘法运算以实现运算复杂度的最小化.同时提出一种改进的快速SPIHT算法,通过使用更多的位来对小波系数进行编码和节省传输分类过程所需的位数以提高压缩性能,这种算法在可变的位码率中可减少系数的相关性.实验结果显示,这种编码对于观察到的压缩图像和进行量化的性能测量,均取得良好效果,同时还能为无线传输提供具有信道误差的弹性功能,最后还使用了带有随机误差的仿真传输信道来对这种功能进行评估和比较.

This paper presents a new image coder with low complexity for real-time transmission,employing edge preservation based on local variance analysis to improve the visual appearance and recognizability of compressed images.The analysis and compression is performed by dividing an image into blocks.Lifting wavelet filter bank with boundary effects minimized is developed with lifting coefficient quantized and implanted by fixed-point arithmetic applying only bit shifting and addition operations to replace multiplications,thus minimizing the computational complexity.A modified SPIHT algorithm with more bits used to encode the wavelet coefficients and transmitting fewer bits in the sorting pass for performance improvement,is used to reduce the correlation of the coefficients at scalable bit rates.Experimental results demonstrate that the method performs well both visually and in terms of quantitative performance measures,and offers error resilience feature that is evaluated using a simulated transmission channel with random error.