Analog median filter circuit for image processing
US6121817A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jan 11, 1999 |
| Grant date | Sep 19, 2000 |
| Priority date | — |
| Expiry date | Jan 11, 2019 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N5/213
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
An analog median filter for rejecting isolated impulse noise while preserving signal step changes in image processing. The analog median filter includes a number of transconductance amplifiers with additional CMOS inverters coupled to the outputs of the amplifiers. The outputs of the inverters are coupled together in a feedback loop configuration with the amplifiers. The CMOS inverters act as a type of additional current source for the amplifiers, so as to sharpen the corners of the transfer curve at various current levels. The low gain of the inverters improve the stability of the output range. Because inverters are used, the feedback loop is coupled to the noninverting inputs of the amplifiers, while the input signals are coupled to the inverting inputs of the amplifiers.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.