Color image processing method and apparatus thereof
US6486981B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Jul 2, 1997 |
| Grant date | Nov 26, 2002 |
| Priority date | — |
| Expiry date | Jul 2, 2017 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N1/642
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A color image processing apparatus which codes image data while suppressing image deterioration. A color character area discrimination unit divides an input color image into 16×16-pixel blocks, and determines whether or not each block expresses color characters. In accordance with the determination result, a sub-sampling ratio switching unit switches the sampling ratio for each of color components YCrCb composing the color image data so that the sample ratio is Y:Cr:Cb=4:2:2 or Y:Cr:Cb=4:1:1. Subsequently, sampling is performed in accordance with the switched sampling ratio, and DCT, linear quantization and entropy coding are then performed.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.