Apparatus and method for nonlinear normalization of image
US5757979A · kind A · utility
Assignees
Inventors
Key dates
| Filing date | Oct 28, 1992 |
| Grant date | May 26, 1998 |
| Priority date | — |
| Expiry date | Oct 28, 2012 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06V30/10
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
A method for nonlinear normalization of an image, which performs pre-processing for computing the correlation between an unknown pattern and a reference pattern. A local spatial density function .rho.(X.sub.i, Y.sub.j) (i=1-I, j=1-J) is calculated from a two-dimensional pattern f(X.sub.i, Y.sub.j) which is obtained by sampling the unknown pattern at a sampling interval .gamma.. The spatial density function .rho.(X.sub.i, Y.sub.j) is obtained as the product of reciprocals of line pitches in both the X and Y directions. An x-direction cumulative function hx(X.sub.i) and a y-direction cumulative function hy(Y.sub.j) are computed by successively adding the space density function .rho.(X.sub.i, Y.sub.j). New sampling points (X.sub.i, Y.sub.j) are computed in such a fashion that new sampling intervals (.delta.i, .epsilon.j), defined as intervals between two adjacent points of the new sampling points (X.sub.i, Y.sub.j), satisfy the condition that a product between the cumulative function hx(X.sub.i) and .delta.i takes a first fixed value, and a product between the cumulative function hy(Y.sub.j) and .epsilon.j takes a second fixed value. The normalized sampled values at the new sampling p…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.