一种基于拷屏和压缩技术的屏幕共享方案

针对当前多媒体应用领域的一类特殊视频——全屏幕半运动非连续色调彩色视频的压缩和传输需求．提出了一种基于拷屏和压缩技术的解决方案．该方案主要利用拷屏和数据压缩技术来实现异地屏幕显示图象的共享,即首先使用拷屏技术从显卡直接获取屏幕图象．然后对拷屏图象进行降低颜色分辨率的处理;接着运用LZ77数据压缩技术进行压缩;最后打包传输。实验证明,该方案不仅可以获得高达100：1以上的图象序列压缩比,并且具有较好的实时性和较低的解码复杂度,因此,可广泛应用于远程教育、股评分析系统等网络多媒体应用领域．

A Screen Sharing Scheme Based on Copying Screen and Data Compression

In multimedia application systems , recently emerging the need of compressing and transmiting a special video in Internet, which has the characters of full screen, half motion and non-continuous tone, for example, the content of PowerPoint files. In order to satisfied this need, this paper proposed an efficient scheme to acheive the high compressed ratio at the same time protecting the nearly lossless visual quality. This scheme is named "sharing screen" and includes the two main techniques, one is called copy-screen, and the other is the data-compression method called LZ77. The first step of this scheme is to copy the full and high resolution screen contents and save them as bitmap formats. The second step is to reduce the color resolution of these bitmap images, transforming the 24bit color definition into 4 or 8 bit color definition so that we can reduced the quantity of image data. The last step is to apply the lossless method to compress the low color resolution images. As to the non-continuous tone color images, the compressed ratio can reach up to 100:1, and it has real time performance, moreover, the decode process is fairly simple. So it can be easily used in network multimedia applications such as Distance Education and Remote Stock Comment & Analysis System.