Enhancing compression while transcoding JPEG images
US7260265B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Oct 4, 2002 |
| Grant date | Aug 21, 2007 |
| Priority date | — |
| Expiry date | Jul 4, 2024 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06T9/007
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
Further compression of data allowing economical storage of data for extended periods of time in high-speed access memory is performed in reduced time by performing further compression during transcoding in the transform domain and without restoring image data to its original image data form. The reduction in processing time is achieved by exploiting the large number of zero-valued quantization transform coefficients and not changing quantized transform coefficients at zig-zag scan positions where non-zero coefficients are rare during range reduction of the entropy decoded quantized transformed data. The range can be restored by computation or estimation of an altered quantization table which is stored with the further compressed a quantization values. Further advantages accrue from use of JPEG packed format for the data during transcoding.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.