Compression method of halftone image data
US4922273A · kind A · utility
52Cited by
6References
16Claims
0Family size
Assignee
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Key dates
| Filing date | Apr 1, 1988 |
| Grant date | May 1, 1990 |
| Priority date | — |
| Expiry date | Apr 1, 2008 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N19/91
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A halftone image data compression method includes steps wherein digital halftone image data is divided into a plurality of blocks, orthogonal transformation is performed in units of blocks to obtain transformed coefficients, and the transform coefficients are quantized and coded. A final quantization interval is determined in units of blocks using a frequency of generation of the AC components of the transform coefficients of each block quantized to zero as a parameter.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.