Bilevel image reducing and enlarging methods and apparatus
US5682251A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | May 7, 1996 |
| Grant date | Oct 28, 1997 |
| Priority date | — |
| Expiry date | May 7, 2016 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N1/3935
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A bilevel image is reduced by dividing the image into N.times.N blocks of pixels, counting black pixels in each block, decrementing the black-pixel count if a certain delayed output value represents a black pixel, and generating an output value by comparing the resulting count with a threshold value. A bilevel image is enlarged by expanding each white pixel into an N.times.N block of white pixels, and each black pixel into an N.times.N block of pixels containing a non-zero number of black pixels, this non-zero number being a non-decreasing function of the number of black pixels in certain positions adjacent to the black pixel being expanded. N is an arbitrary integer greater than one.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.