Digital watermarking which allows tampering to be detected on a block-specific basis
US7545938B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Nov 10, 2003 |
| Grant date | Jun 9, 2009 |
| Priority date | — |
| Expiry date | Feb 11, 2026 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06T2201/0083
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
An apparatus for generating codes includes a quantization unit which generates quantization coefficients by performing discrete wavelet transform with respect to each of tiles into which an image is divided, a block division unit which divides the quantization coefficients into blocks, a Hash conversion unit which performs Hash conversion based on the quantization coefficients of each of the blocks so as to produce a Hash value for each of the blocks, a digital watermark embedding unit which adjusts a parity of a quantization coefficient of interest equal to a parity of the Hash value of a block to which the quantization coefficient of interest belongs, and a coding unit which generates code sequence data by coding the quantization coefficients including the quantization coefficient whose parity is adjusted.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.