Color modifier for composite video signals
US4533938A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Dec 20, 1982 |
| Grant date | Aug 6, 1985 |
| Priority date | — |
| Expiry date | Dec 20, 2002 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N9/68
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
Hue and saturation are modified in a composite video signal processor by detecting the phase of the chrominance signal component to determine if it possesses phase components at or near a predetermined phase angle. If such components exist, quadrature related saturation and hue modifying signals are added to the composite video signal in controlled proportions and polarities to provide a resultant composite video signal in which a specified color or range of colors is modified. The modifying signals are inhibited by a masking unit to confine the color modification to predetermined areas of the displayed color image. Specific picture locations where color changes occur are identified by substituting an AC signal within the luminance frequency band for the color modifying signals. A desaturation signal derived from the hue modifying signals is added to the composite video signal to minimize changes in saturation level of the composite video signal as hue is changed.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.