OPTIMAL WAVELET FILTER DESIGN FOR REMOTE SENSING IMAGE COMPRESSION

A new approach for designing the Biorthogonal Wavelet Filter Bank (BWFB) for the purpose of image compression is presented in this letter. The approach is decomposed into two steps. First, an optimal filter bank is designed in theoretical sense based on Vaidyanathan’s coding gain criterion in SubBand Coding (SBC) system. Then the above filter bank is optimized based on the criterion of Peak Signal-to-Noise Ratio (PSNR) in JPEG2000 image compression system, resulting in a BWFB in practical application sense. With the approach, a series of BWFB for a specific class of applications related to image compression, such as remote sensing images, can be fast designed. Here, new 5/3 BWFB and 9/7 BWFB are presented based on the above approach for the remote sensing image compression applications. Experiments show that the two filter banks are equally performed with respect to CDF 9/7 and LT 5/3 filter in JPEG2000 standard; at the same time, the coefficients and the lifting parameters of the lifting scheme are all rational, which bring the computational advantage, and the ease for VLSI implementation.

基于ROI的压缩域多谱段遥感图像的检索

根据JPEG2000对感兴趣区域优先编码,以及感兴趣区域的形状可随意选取的特点,提出了一种在JPEG2000压缩码流不完全解码的情况下,实现多谱段遥感图像感兴趣目标的检索方法,该方法利用了遥感图像的性质,根据例子图像的谱特征对感兴趣区域的内容进行分析,并设计了一套相似性度量的方法。实验结果表明,此方法有较理想的图像检索效果和很高的检索效率,解决了应用上对实时性的高要求与遥感图像库数据海量性之间的矛盾。

JPEG 2000和JPEG-LS的实现及遥感影像压缩失真分析

JPEG 2000和JPEG-LS是目前应用比较广泛的两种压缩算法。本文介绍了JPEG 2000和JPEG-LS的编码流程、实现方法,通过试验分别分析了遥感影像在不同压缩比下的失真程度大小以及不同的失真类型。结果表明:在相同的中低倍压缩比条件下,JPEG 2000和JPEG-LS在影像细节信息保持方面效果非常接近;在高倍压缩比下,JPEG 2000和JPEG-LS压缩后影像分别出现了明显的模糊失真和间歇性失真现象。本文分析结论对相关算法的使用和改进有一定的借鉴意义。

JPEG 2000编码参数对遥感影像压缩质量的影响

离散小波变换和EBCOT编码是JPEG 2000标准的核心技术,调整其编码参数对图像压缩性能有重要影响。将压缩后影像与原始影像做对比,通过大量实验重点分析小波变换级数和码块大小对不同压缩倍率下重建图像质量的影响,并给出不同压缩比下编码参数的适宜取值范围。实验结果表明,影像进行中、低倍率压缩时,可以设置较低的小波变换级数(2级或3级)和较小的码块大小(如8×8或16×16)对图像进行编码;影像进行较高倍率压缩时,需要设置较高的变换级数(4级或5级)和较大的码块大小(如32×32)使图像获得较高的重建质量。相关结论为影像压缩实际参数的选择提供依据。