JPEG 2000压缩对遥感影像监督分类精度的影响

遥感图像压缩会影响分类精度,是值得研究的问题。以高分辨率遥感影像(Quick Bird)的监督分类精度评定为尺度,采用ER Mapper软件的JPEG 2000图像压缩模块对图像进行压缩,再在eCognition软件中对这9种压缩比图像进行面向对象的监督分类,生成分类精度报告。通过分析分类精度的变化,研究了JPEG 2000压缩对遥感影像分类的影响程度及其在遥感影像压缩方面的应用潜力。     

基于模糊综合评判方法的遥感影像压缩主观质量评价

介绍遥感影像压缩的主观评价方法及其分类,并应用模糊综合评判方法对采用JPEG2000标准和SPIHT改进算法压缩后的重建影像进行质量评价。评价结果表明:随着压缩比增加,两种压缩算法压缩后的影像质量均逐渐下降;当压缩比不超过4∶1时,两种压缩算法得到的影像效果均较好,与原始影像差别不大;当压缩比相同时,JPEG2000算法的压缩效果略好于SPIHT算法;在地形较复杂的丘陵和山地,两种压缩算法压缩后的影像质量下降,影像失真较严重。     

网络环境下的遥感影像金字塔纹理压缩算法与实验

 建立不同分辨率的遥感影像金字塔模型是现阶段虚拟地球平台的主要技术手段,遥感影像数据的高效压缩是模型应用的基础。论文在分析多种图像压缩技术的基础上,提出以小波变换的JPEG2000标准来压缩网络环境中遥感影像金字塔的纹理瓦片数据。首先,介绍了小波变换的JPEG2000标准的基本原理和EBCOT算法特点,然后,结合实例实现了网络环境中遥感影像金字塔纹理压缩/解压缩的具体过程,对4幅影像图像进行5级离散小波变换,分别对在1024×1024、512×512、256×256、128×128、64×64不同分块大小和1∶15、1∶30、1∶60不同压缩倍率情况下进行图像压缩和重构耗时实验,通过改变分块大小参数和压缩倍率,对压缩性能进行了对比分析,最后,从主观视觉质量和客观辐射质量,对JPEG2000压缩、DXT压缩和JPEG压缩几种方法的压缩图像进行了评价与对比分析。实验结果表明,小波变换的JPEG2000具有高质量、高压缩率、良好的抗误码能力等特性,重构图像的视觉质量与原始图像相比人眼看不出失真,而峰值信噪比较好,是一种简单有效、易于快速实现的压缩方法,更适合于网络环境下空间遥感图像数据的近无损实时压缩。     

Effects of Jpeg Compression on the Accuracy of Digital Terrain Models Automatically Derived from Digital Aerial Images

It is well recognised that data volume represents a huge overhead for softcopy photogrammetry. For example, a file size of 100 Mbytes will be generated from a black and white aerial photograph if digitised with a resolution of 20μm. Large data volumes not only create storage problems but also affect the speed of image processing. As a consequence, data compression of image data is a matter of great significance. This paper describes an investigation into the effects of image compression on the accuracy of digital terrain models (DTMs) extracted from the compressed images. The JPEG system implemented in the Z/I Imaging ImageStation digital photogrammetric workstation (DPW) was used in the study. A systematic test has been carried out on the effect of different levels of JPEG compression (with Q-factors from 1 to 100) on the resulting DTM, which is automatically generated by the DPW using Match-T software. An analysis of the results from the two sites tested shows that image compression tends to cause more significant degradation when the image texture is richer, but that recommendations on Q-factors for use with the ImageStation appear to err on the side of caution. This analysis leads to some tentative conclusions and recommendations both for future investigation and for photogrammetric practice.     

Effects of jpeg 2000 compression on automated dsm extraction: evidence from aerial photographs

This paper evaluates the effects of JPEG 2000 compression on automated digital surface model (DSM) extraction, using the area-based matching technique. Two stereopairs of aerial photographs, which have different photo scale, pixel size, and topographic type, are used as the images for the experiments. In the experiments, the DSM generated from the uncompressed image is set as the reference, and the elevation accuracy is computed for a range of compression ratios (2:1 to 100:1). The results show that the employed indices of image quality based on the JPEG 2000 compression are clearly superior to the commonly used JPEG compression technique—especially for high compression ratios. However, the elevation accuracy varies with the compression ratios. Also, JPEG 2000 compression does not have a significant influence on the percentage of the successful matching rate. In addition, a near linear fall-off is observed in extracted DSM accuracy with increasing compression ratios.     

基于数字区域软件平台的JPEG压缩与网络传输

Google Earth作为一个全球性的商业应用软件,不可能面向区域展开针对性的应用。而数字区域作为数字地球的重要部分,侧重于区域范围的空间信息应用与共享,具有非常重要的应用价值与前景。本文在简述数字区域软件平台设计的基础上,分析了JPEG静态图像压缩标准,并应用于数字区域软件平台中,最后利用VC .NET实现基于该平台的压缩与网络传输。     

JPEG压缩对摄影测量点定位精度的影响

对某城区一对1：8000航摄立体数学影像利用Intergraph数字摄影测量工作站上的立体量测软件ISDM进行了手上量测，然后通过用自行开发的GPS辅助光束法区域风平差软件WuACPSGPS的单模型光束法平差精确测定了18个加密点的位置，经过对数字影像采用1到100不同的质量因子的JPEG压缩，获得一组质量各异的压缩影像，从分析重建影像点定位结果的变化入手，探讨了JPEG压缩对摄影测量点定位精的影响。试验且明，失真JPEG压缩对摄影测量点定位精度的影响是显著的，随着压缩比的增大，影像可视化质量逐渐衰减，像点量测精度不断降低，加密点位精度几乎呈线性趋势下降，且高程比平面减的速度要快得多。     

影像入库及管理系统

影像信息是表示地理信息的最直观最有效的辅助手段之一。文中提出了一种网络环境下影像信息入库、管理的一种方法，目的在于实现影像数据的有效管理以及快速高效的数据保障。     

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。     

Comparative geometric and radiometric evaluation of mobile phone and still video cameras

This paper examines the potential of mobile phones to be used as front-end sensors for photogrammetric procedures and applications. For this purpose, two mobile phone cameras (Sony Ericsson K750i and Nokia N93) were calibrated over an indoor 3D testfield, using a self-calibrating bundle adjustment. Geometric accuracy tests were carried out in order to evaluate their metric performances and to compare the results with respect to two off-the-shelf digital still video cameras (Sony DSC W100 and Sony DSC F828). The geometric accuracy evaluation comprised an absolute accuracy test, JPEG test and temporal stability test. The radiometric capabilities of all cameras (except that the DSC W100 was replaced with a DSC T100 camera) were also evaluated and compared by carrying out modulation transfer function (MTF) analysis, image noise analysis and an operating range test. Substantial systematic errors were diagnosed in some systems. However, with proper calibration it is believed that these devices can be used for many photogrammetric tasks.