Processing images using two-dimensional forward transforms
US5638068A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jun 1, 1995 |
| Grant date | Jun 10, 1997 |
| Priority date | — |
| Expiry date | Jun 1, 2015 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04Q2213/13337
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
Images are encoded by applying a two-dimensional forward transform to blocks of pixels or pixel differences to generate transform coefficients for each block. The two-dimensional transform is decomposed into two phases: (1) a first phase in which a first one-dimensional transform (e.g., a row transform) is applied to the input block using forward mapping, where the inputs are used as indices to lookup tables to retrieve contributions to intermediate coefficients, and (2) a computational phase in which a second one-dimensional transform (e.g., a column transform) is applied to the intermediate coefficients to generate the transform coefficients. In a preferred embodiment, a forward discrete slant transform is implemented using pseudo-SIMD techniques to reduce the total numbers of lookup tables, table lookups, and column transform computations.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.