Coding apparatus
US5307163A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Mar 11, 1993 |
| Grant date | Apr 26, 1994 |
| Priority date | — |
| Expiry date | Mar 11, 2013 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N19/91
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A coding apparatus, in which each block having a plurality of picture elements with digital image signals is divided into a plurality of sub-blocks, and an appropriate quantization step or weighting factor is decided on the basis of the absolute value sum of difference of image signal level between adjacent picture elements in the sub-block, so that a digital image signal is reduced. Moreover, a coding apparatus, in which each block having a plurality of picture elements with digital image signals is divided into a plurality of sub-blocks, and an appropriate quantization step or weighting factor is decided on the basis of the maximum and minimum values of the image signals of the picture elements in the sub-block, so that a digital image signal is reduced. Accordingly, in the coding apparatus as above, the state of the image is recognized for every block, whereby a block whose degradation of image quality is hard to notice at the decoder side is quantized or subjected to weighting with low rate, that is, with large reduction rate, whereas a block whose degradation of image quality is conspicuous at the decoder side is quantized or subjected to weighting with high rate, i.e., with s…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.