Image compression apparatus using a lossy compression method
US5506916A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Nov 25, 1992 |
| Grant date | Apr 9, 1996 |
| Priority date | — |
| Expiry date | Nov 25, 2012 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N19/91
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
An image compression apparatus has a separation section for performing processing for dividing image data into a plurality of data blocks, an orthogonal transformer for orthogonal-transforming each data block, a bit allocation table for storing data representing the number of bits allocated in accordance with the frequency component of the orthogonal-transformed data output from the orthogonal transformer, an arithmetic operation circuit for calculating an amplitude probability density function of an identical frequency component of the orthogonal-transformed image data for each pixel, and calculating a quantization limit band causing a mean square error to be minimized in acordance with the calculating amplitude probability density function and the bit-number data from the bit allocation table, and a band limit table for storing the quantization limit band data. A quantizing circuit quantizes the orthogonal-transformed block information from the orthogonal transformer in accordance with the data stored in the allocation table and the band limit table.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.