Method for detecting rotation and magnification in images
US5835639A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 18, 1996 |
| Grant date | Nov 10, 1998 |
| Priority date | — |
| Expiry date | Dec 18, 2016 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06V10/243
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
A method for detecting an amount of rotation or magnification in a modified image, includes the steps of: embedding a marker image having a pair of identical features separated by a distance d and oriented at an angle .alpha. in an original image to produce a marked image, the marked image having been rotated and/or magnified to produce the modified image; performing an autocorrelation on the modified image to produce a pair of autocorrelation peaks corresponding to the location of the features of the marker image in the modified image; and comparing the separation d' and orientation .alpha.' of the autocorrelation peaks with the separation d and orientation .alpha. of the features in the marker image to determine the amount of rotation and magnification in the modified image.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.