两种基于部分加密的图像和视频加密方案

某些多媒体加密并不要求加密后的信息完全不可理解，例如，在图像传输中可能只要求对其中某个人、物或区域部分加密；在视频点播中可能只要求将原始画面变得模糊，而其中的轮廓可见。正是基于以上两点，文章提出两种部分加密方案：基于分层编码的部分加密方案和基于目标的部分加密方案。并分别以小波变换的分层编码方法SPIHT和DCT变换的分块编码方法JPEG为例，分析了以上两种加密方案的效果和可能的应用前景。

Two Kinds of Image or Video Encryption Schemes Based on Partial Encryption

In some multimedia applications, it is not absolute that multimedia data is encrypted completely. For example, in image transformations, only some sensitive regions (man, object, etc.) in a picture are required to be protected, and other regions can remain unchanged. In VOD (video-on-demand) systems, videos are only required to be blurred, but their content can still be understood, thus if customers like them, they will buy the high definitional ones. Inspired by these applications, two kinds of partial encryption schemes are proposed in this paper. One is the partial encryption scheme based on progressive image or video encoding, and the other is the partial encryption scheme based on object-based image or video encoding. In these algorithms, multimedia data is encrypted partially or selectively. In experiments, the encryption algorithms combining with SPIHT and JPEG codecs are tested and analyzed. Experimental results show that both of them are suitable for future applications.