Method and apparatus for encoding and decoding dither signals for reproduction of the halftone of a picture
US4766499A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jul 10, 1987 |
| Grant date | Aug 23, 1988 |
| Priority date | — |
| Expiry date | Jul 10, 2007 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06T9/004
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
On the transmitting side of a facsimile system, a predictive picture signal x.sub.ij of a pel (i, j) is obtained, taking account of predictive picture signals of pels prior to the pel (i, j), which have been previously obtained. A two-level transposition signal d.sub.ij is determined in accordance with the predetermined on the basis of an actual picture signal x.sub.ij, the predictive picture signal x.sub.ij and a dither threshold t.sub.ij. The thus obtained transposition signal d.sub.ij is encoded by use of the MH or MR coding method and transmitted to a receiving side of the facsimile system. Compared with the conventional case, in which a dither signal z.sub.ij itself is encoded and transmitted, the transposition signal d.sub.ij can be considerably compressed, when it is encoded for transmission by use of the MH or MR coding method.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.