Image reader that stores sets of luminance correction data corresponding to document a surface height
US5969829A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Sep 18, 1997 |
| Grant date | Oct 19, 1999 |
| Priority date | — |
| Expiry date | Sep 18, 2017 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N2201/0434
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
An image reader capable of outputting excellent quality read images, without illumination irregularities, similar to that of flat documents even when the document surface is curved as in the case of book-like documents. An image reader provided with a memory to store correction data to correct differences of illumination of each pixel of a document image, and which corrects the read information of each pixel in a document image using correction data corresponding to the measured height of a document surface among correction data stored in the memory. For one aspect, this image reader is constructed so as to correct a group of read information corresponding to a set of pixels arrayed in one direction by excluding specific frequencies among the illumination distribution from the set.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.