Block size assignment using local contrast ratio
US6996283B2 · kind B2 · utility
Assignee
Inventor
Key dates
| Filing date | Nov 15, 2002 |
| Grant date | Feb 7, 2006 |
| Priority date | — |
| Expiry date | Jan 28, 2024 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N19/96
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
An apparatus and method for determining a block size assignment for a block of pixels is claimed. A mean for a given block of pixels and a neighborhood mean for adjacent blocks of pixels is determined. A contrast ratio is then determined, as a function of the mean and the neighborhood mean. A variance threshold is determined as a function of the contrast ratio. Then, various sub-block sizes within the block of pixels is determined as a function of the variance threshold. As such, a pixel block is considered in the context of adjacent pixel blocks rather than in isolation, which narrows the spread of block variances and allows for a more robust subdivision of pixel blocks.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.