Data processor for image data using orthogonal transformation
US5517327A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jun 28, 1994 |
| Grant date | May 14, 1996 |
| Priority date | — |
| Expiry date | Jun 28, 2014 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N19/30
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
In a data processor, image data of a pixel matrix is subjected to orthogonal transformation to coefficient data, the coefficient data is quantized with a first quantization table for character image and a second quantization table for half-tone image, and the image data is discriminated to be character image data or half-tone image data according to the quantization data. The selected data is then coded. In another processor, image data are divided into first and second processing blocks of m*m and M*M pixel matrices wherein M>m and the second processing block includes one of first processing blocks and adjacent pixels. Image data in a first and second processing block are subjected to orthogonal transformation to coefficient data. It is discriminated according to the coefficient data of the second processing block if the image is a character, dot, or half-tone image to select an appropriate quantization table, and image data of the first block is quantized according to the selected table and the quantized data are coded. In a further processor, two discrimination windows are provided, the first having coefficient data around the DC component and the second having the other data. O…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.