Circuit for enhancing a color difference signal by utilizing the change of a luminance signal
US4980755A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jan 19, 1990 |
| Grant date | Dec 25, 1990 |
| Priority date | — |
| Expiry date | Jan 19, 2010 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N9/646
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
An enhancing circuit wherein a color difference signal (b) is enhanced by utilizing the change of a luminance signal (a). The luminance signal (a) is sent, via a low-pass filter (2), a first delay circuit (3), a first differentiation circuit (4), a detector (5), a slicer (6), and a second differentiation circuit (7), to a comparator set (8) to produce two signals (i and j). The two signals (i and j) are sent to first and second sample-and-hold circuits (11 and 12). Meanwhile, the color difference signal (b) is delayed in a second delay circuit (10). In these two sample-and-hold circuit (11 and 12), such a delayed color difference signal (c) and color different signal (b) are respectively held in response to the two signals (i and j). Then, such two held signals (I' and II') and the delayed color difference signal (d) are sent to a switching circuit (13) for selecting one of these three signals (I', II', III') in accordance with the combination of the two signals (i and j) thereby producing an enhanced color difference signal (k). Since the luminance signal (a) has a wide frequency band, color-ringing of an image can be satisfactorily reduced.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.