Apparatus for enhancing and thresholding scanned microfilm images and methods for use therein
US4982294A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jul 24, 1987 |
| Grant date | Jan 1, 1991 |
| Priority date | — |
| Expiry date | Jul 24, 2007 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N1/409
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
Apparatus for enhancing and thresholding scanned microfilm images, specifically for removing single pixel noise therefrom, and accompanying methods for use therein are disclosed. Specifically, this apparatus convolves each one of a pre-defined group of incoming pixel values with a corresponding one of a pre-defined set of coefficients in order to generate an convolved pixel value. The convolved pixel is then compared against a threshold level to produce a thresholded pixel value indicative of the results of the comparison. The inventive apparatus also includes a noise processing circuit that contains a noise tracker and a noise detector and filter circuit. The noise tracker is used to produce a noise value that tracks a noise level present in the threshold pixel value. The noise detector and filter circuit filters pixel noise from the thresholded pixel value and, in response thereto, produces a corresponding output pixel value for a current incoming pixel value being processed and provides a signal to the noise tracker that pixel noise has been detected. A background tracker, which also forms part of the inventive apparatus, produces a background value that tracks a background leve…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.