Buffer Mechanism for Pel Positioning of Multiple Video Images, Including Overlapping, on a Raster-Scan CRT
Original Publication Date: 1987-Apr-01
Included in the Prior Art Database: 2005-Feb-01
A buffer mechanism allows multiple video images to be individually positioned at any pel location on the screen of a raster-scan CRT. The images may overlap each other and do so in a controlled manner. The buffer mechanism (Fig. 1) has five parts: the Loader 11, the VDE Buffer 12, the Transformer 13, the Scan Buffer 14, and the Displayer 15. Loader 11 adds VDEs to VDE Buffer 12. VDEs are stored in the Buffer 12 for as long as they are needed by Transformer 13 and are then discarded to make room for new VDEs. Transformer 13 uses the VDEs to generate the pels (picture elements) for a full scan and stores them in Scan Buffer 14. Displayer 15 reads and displays the Scan Buffer contents. The information in or associated with each VDE is the image origin, OI = (XI, YI) and dimensions, WI x HI, shown in Fig. 2.