Controlling the combining of video signals
US5046165A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jan 24, 1990 |
| Grant date | Sep 3, 1991 |
| Priority date | — |
| Expiry date | Jan 24, 2010 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N5/2622
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
Apparatus for controlling the combining of video signals includes a field rate microprocessor (10) that generaes edge data defining the edges of a polygonal first picture (KP) which is to be keyed into a second picture (B) to produce a composite picture. Two line rate microprocessors (16, 18) generate from the edge data, for each horizontal scanning line of the composite picture in which a row of pixels corresponding to that scanning line is intersected by edges of the first picture, signals representing: the horizontal locations of first and second start pixels, namely those of the row of pixels in which first and second edges (e.g. Eb, E2), respectively, of the first picture (KP) start to intersect the row; the gradients of the first and second edges; and a key value (the proportion of the first picture to be contained in a pixel of the composite picture) for each of the first and second start pixels. A key value generator (32) generates, for each scanning line of the composite picture, a key value for each successive one of the row of pixels corresponding thereto, by: ramping up the key value from zero, for pixels preceding the first start pixel, by incrementing the key value fo…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.