Television scan conversion for computer graphics

摘要

The work to be described herein was a section of theInter graphic project which was carried out at the Universityof New South Wales, Inter graphic was the name given to agraphical interface computer, designed to operate as aninput/output device to a major computer and to provideaccess from a number of graphical terminals. The outputsof the graphical interface are voltages corresponding tothe X and Y coordinates of a trace which can be appliedto a cathode ray tube to produce a graphical display.For reasons of economy, the Inter graphic output isnon repetitive and the X-Y form is not suitable for distribution.It is therefore to be converted to a fullyinterlaced television image and stored on a video discrecorder for repetitive reproduction and distributionto television receivers at the computer terminals.Preliminary investigation was made into possiblemethods of scan conversion from the X-Y form to televisionand the method chosen was that using a television camerascanning a cathode ray tube display. Various types oftelevision camera tubes were examined and the Plumbiconwas chosen as the most suitable tube for this application.An experimental converter was constructed by adding to acommercially available camera and it was tested usinga cathode ray oscilloscope as a source of graphical images.