Preserving dynamic range precision in integer image formats
US9369739B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Oct 28, 2014 |
| Grant date | Jun 14, 2016 |
| Priority date | — |
| Expiry date | Feb 24, 2035 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N23/741
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
High dynamic range media sensor output is encoded using a hybrid transfer function. The hybrid transfer function conforms to existing industry standards over standard brightness level ranges, such as between black and white reference points, and uses a different function to encode captured signals having intensities below the black point and above the white point. Precision over the expanded dynamic range of captured image data is optimally preserved using a two-byte per pixel representation. The transfer function varies across the full dynamic range without clamping off below the maximum value of the expanded captured intensity range. One hybrid transfer function conforms to BT.1886 up to the white point, and uses a linearly varying encoding gamma above the white point up to 1300% IRE, producing encoded values in a 2.14 fixed point representation. The hybrid transfer function is continuous at the white point, and may also have a continuous gradient there.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.