Drawing processor including arithmetical unit for improved superposed picture display
US5109480A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 12, 1989 |
| Grant date | Apr 28, 1992 |
| Priority date | — |
| Expiry date | Dec 12, 2009 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06F2207/3828
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A color graphic display system is disclosed including a drawing process for displaying video data on a display device wherein the data is particularly intended to include superposed pictures. The processor includes an arithmetical operation unit which will allow addition/subtraction of video data items representative of the picture elements to be superposed. Further included is a condition setting circuit for selectively inhibiting carrys or borrows during the arithmetical operations between selected bits of a data word representative of an element such as a pixel of the picture being displayed. More particularly, where a video data item is comprised of sets of bits each set of which is representative of a main color of the pixel, and when two video data items are added or subtracted, the carrys that may normally occur between the different sets are inhibited to avoid interference between the sets that may affect the color of the resulting video data item. A carry look-ahead circuit is also provided for improved processing speed of the system. An overflow prevention circuit is disclosed for forcibly switching selected bits of the video data item to a preselected value upon determin…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.