林业专题图数字水印版权保护研究

Copyright Protection Research on Forestry Thematic Maps Using Digital Watermarking

针对林业专题图制作过程复杂、成本高、迫切需要进行版权保护的问题,分析了JPEG图像压缩的不变属性,在此基础上提出了一种DCT域数字水印算法,该算法将水印信息嵌入到JPEG格式的林业专题图像的中高频系数当中。结果表明:因为水印信息是嵌入在中高频系数上,所以不仅嵌入的水印信息不可感知性良好,而且水印的嵌入容量也有所增加;即使对加密林业专题图进行有损压缩时使用高于预设值的质量因子,此算法仍然能够完全一致地提取出嵌入的水印信息,并且对各种噪声干扰都具有较好的鲁棒性。

Aiming at the problems of complicated production process, high-cost and urgent need for copyrightprotection of forestry thematic maps, the invariant property of JPEG image compression was analyzed. On thisbasis, a DCT digital watermarking algorithm, in which watermark information was embedded in median andhigh frequency coefficients of forestry thematic maps using JPEG format, was proposed. The results showedthat the algorithm had better imperceptibility and larger embedding capacity because the watermarkinformation was embedded in the median and high frequency coefficients. Even if using lossy compression toencryption forestry thematic maps with quality factor that higher than preset value, the algorithm could exactlyextract embedded watermark information, and had good robustness against noisy.