基于DCT域数字水印技术的DEM版权保护研究

探索适用于DEM的近无损自适应数字水印算法,以期为DEM版权保护提供有效的解决方案。首先,将水印嵌入在DEM地性线位置,以增强水印鲁棒性,实现水印嵌入位置的自适应。其次,从理论上研究在DCT域内,采用加性水印嵌入规则时,如何根据给定的DEM精度,并结合Watson视觉模型确定水印嵌入强度的问题,避免以往研究中或者通过反复实验确定嵌入强度,费时费力,或者由视觉模型确定而不能满足DEM精度要求的缺点,同时实现水印嵌入强度对地貌类型的自适应。结果表明,该算法既能满足水印的不可见性,又能实现DEM精度的近无损和提取等高线的近无损性要求,且具有良好的抗JPEG压缩、JPEG2000压缩和几何裁剪的能力。

Copyright Protection of DEM by Means of DCT-based Digital Watermarking

A near-lossless,adaptive watermarking algorithm based on DCT is presented to protect DEM from theft and illegal reproduction.The contribution of this work is twofold: ①In order to improve robustness,the methodology is designed to embed a watermark in terrain lines.②As for the watermark embedding strength,it is decided theoretically in DCT domain by jointing the elevation precision of DEM and Watson perceptual model.And since different precision requirements are given to different relief forms,the watermark embedding strength is adaptive to relief forms.The experiments show satisfying results are not only in watermark transparency,but also in near-lossless of DEM precision and contour derived from watermarked DEM.In addition,this algorithm shows robustness towards JPEG compression,JPEG2000 compression and cropping attacks.