AN ADAPTIVE DIGITAL IMAGE WATERMARK ALGORITHM BASED ON GRAY-SCALE MORPHOLOGY

An adaptive digital image watermark algorithm with strong robustness based on gray-scale morphology is proposed in this paper.The embedded strategies include:The algorithm seeks and extracts adaptively the image strong texture regions.The algorithm maps the image strong texture region to the wavelet tree structures, and embeds adaptively watermark into the wavelet coefficients corresponding to the image's strong texture regions.According to the visual masking features, the algorithm adjusts adaptively the watermark-embedding intensity.Experimental results show the algorithm is robust to compression, filtering, noise as well as strong shear attacks.The algorithm is blind watermark scheme.The image strong texture region extraction method based on morphology in this algorithm is simple and effective and adaptive to various images.

面向多用户的高动态范围视频动态范围可分级编码

提出了面向多用户的高动态范围(HDR,high dynamic range)视频动态范围可分级编码方法,并利用视觉掩蔽特性抑制了噪声,提高了动态范围可分级编码的效率。首先,考虑HDR视频感知特性,提出了动态范围可分级模型(DRSM,dynamic range scalable model),将不同动态范围级的HDR视频分解成为一个标准动态范围(SDR,standard dynamic range)视频和多个残差信号帧(RSFs,residual signal frames)序列。然后,结合亮度掩蔽效应和人眼感知特性,对RSFs进行量化和滤波处理,滤除残差中的零散数据点,保留RSFs相邻动态范围级之间的整体差异信息,提高RSFs的编码效率。最后,在解码端重建得到SDR视频和各个动态范围级的HDR视频,以适应多用户端MDR显示设备。结果表明,所提出方法能在保持重建HDR视频的主观感知质量的同时降低编码码率,并在全帧内预测编码模式下,相同HDR-VDP-2.2和PSNR分值时,BD-rate(Bjntegaard Delta rate)平均节省了32.03%和31.28%,其编码率失真性能有明显提升。