Method for determining noise in radiography
US7324678B2 · kind B2 · utility
Assignee
Inventor
Key dates
| Filing date | Oct 1, 2003 |
| Grant date | Jan 29, 2008 |
| Priority date | — |
| Expiry date | Jul 27, 2025 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06T2207/10116
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
In order to model a fluoroscopic noise present in a radiography operation, two successive images of a same zone are used so that it is possible to pair the dots of the two images as a function of the zone of the space that they represent. The pairs of dots are grouped in sub-groups according to their gray level. For each sub-group, the mean standard deviation σ of the Pi(x, y)−Pi−1(x, y) values is computed. A sub-group is discriminated by eliminating the dots for which Pi(x, y)−Pi−1(x, y) is greater than the mean of the values Pi(x, y)−Pi−1(x, y) plus k times the mean standard deviation. These computations are repeated a certain number of times. Once the sub-group is discriminated, its centering is assessed. A sub-group is non-centered if its mean is greater than 1.5 times its mean standard deviation. Pairs of dots (v, σ) are then obtained. From these dots, an iterative regression is performed to obtain a model of noise according to σ(v)=α.√v+β.v+γ, where v is the gray level and α, β and γ are coefficients defining the noise.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.