一种基于排序的JPEG码流无损水印算法

提出了一种基于排序的直接在JPEG码流中嵌入水印的算法,该方法在保证嵌完水印后图像无失真的条件下提高了嵌入容量.根据对JPEG图像中可变长度码使用情况的统计分析,通过将一幅图像中没有使用过的可变长度码映射为使用过的可变长度码来嵌入水印.在建立映射关系之前,首先对码流中出现过的可变长度码依据其在码漉中出现的频率进行排序,然后使用排序后的结果建立映射关系,从而提高可变长度码的利用率,进而提高嵌入容量.在水印嵌入过程中,根据相应的映射关系和水印信息将码流中出现的可变长度码替换为映射的可变长度码.分析和实验结果表明,这种方法能够实现较高容量的水印嵌入,并且嵌完水印后图像无失真.

Embed Lossless Watermark in JPEG Bitstream Based on Sorting

This paper proposed a modified scheme of embedding watermark in JPEG bitstream based on sorting, the motivation for this method is that it ensure the cover image is lossless after embedding the watermark and improve the embedding capacity. According to the statistical results of VLC usage in an image, we embed watermark by mapping an unused VLC to a used VLC. Sort the VLC(s) according to their appear rate in the bitstream before mapping, it will improve the VLC utilization rate and increase the embedding capacity after sorting. During the data embedding, we replace the codes appearing in the bitstream by the mapped codes according to the watermark. The results can proved that the proposed method has high embedding capacity and can preserve the image with no quality distortion.