Image reading apparatus with data density and gamma correction means
US5929417A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | May 29, 1997 |
| Grant date | Jul 27, 1999 |
| Priority date | — |
| Expiry date | May 29, 2017 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N1/4076
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
An image reading apparatus in which reference density data corresponding to a reference document having a predetermined reference density is stored in advance, while a plurality of gamma correction curves are also stored in advance. Light intensity data indicative of the intensity of light reflected from the reference document is subjected to a shading correction. One gamma correction curve is selected from the plurality of gamma correction curves in correspondence to a difference in output level between the reference density data and outputted density data obtained by converting the shading corrected light intensity data. Gradation of the outputted density data is adjusted based on the selected gamma correction curve.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.