Method of discriminating different kinds of image areas, involving two-dimensional orthogonal transforms
US5101438A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jan 24, 1991 |
| Grant date | Mar 31, 1992 |
| Priority date | — |
| Expiry date | Jan 24, 2011 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N1/40062
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
An image area discriminating method surely distinguishes a character image area and a halftone image area printed on a single document in response to image data outputted by an image reader. An image of interest is divided into N.times.N blocks and subjected to two-dimensional orthogonal transform block by block to produce an N.times.N coefficient pattern. The blocks each is compared with coefficient patterns prepared beforehand and matching the characteristics of character images to see if the block lies in a character image area or in a halftone image area. The N.times.N coefficients may be replaced with N.times.N vectors. Then, a necessary number of vectors are selected out of the N.times.N vectors to generate a .upsilon.-dimensional coefficient vector, and it is compared with vecotrs prepared beforehand for character identification and matching the characteristics of character images.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.