(上接第09/10期)2图形的坐标系在图形系统中,为了表示出各图形元素间的位置关系,需要有统一的坐标系。基于不同目的,MHP包含可列坐标系。根据需要这些坐标系可以相互转换,主要有以下3种。(1)输入视频空间:视频图像采样的像素空间;(2)设备空间:为不同显示设备的逻辑像素,可以有 (Continued on the 09/10) 2 graphics coordinate system In the graphics system, in order to show the positional relationship between the various graphic elements, you need to have a uniform coordinate system. For a different purpose, MHPs contain a listable coordinate system. According to the needs of these coordinate systems can be converted to each other, there are the following three kinds. (1) input video space: pixel space for video image sampling; (2) device space: logical pixels for different display devices, there may be