Method and apparatus for determining feature points
US5694487A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | May 4, 1995 |
| Grant date | Dec 2, 1997 |
| Priority date | — |
| Expiry date | May 4, 2015 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06T7/246
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A method for determining feature points comprises a step for (a) providing directional gradients and a gradient magnitude for each pixel in the video frame, (b) normalizing the directional gradients by dividing the directional gradients with the gradient magnitude, (c) generating a first edge map having the gradient magnitude for each pixel, (d) generating a second edge map having the normalized direction gradients for each pixel, (e) dividing the first edge map into a plurality of blocks of an identical size, (f) providing, for each of the pixels included in each of the blocks, normalized directional gradients for a set of a predetermined number of pixels from the second edge map, (g) obtaining a variance for each of the pixels included in each of the blocks based on the provided normalized directional gradients, (h) determining a feature point for each of the blocks based on the gradient magnitude and variance corresponding to each of the pixels therein.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.