Method of recognizing faces using range images

Claim 3

A method of comparing a three-dimensional facial image with a two-dimensional intensity image of a face as defined in claim 1 wherein the correlation results are substantially independent of angle of illumination of a face within the two dimensional intensity image.

Claim 4

A method of comparing a three-dimensional facial image with a two-dimensional intensity image of a face as defined in claim 1 wherein the step of performing a correlation comprises the steps of transforming the two-dimensional intensity image before filtering the provided transform, and transforming the filtered transformed two-dimensional intensity image to produce the correlation result.

Claim 5

A method of comparing a three-dimensional facial image with a two-dimensional intensity image of a face as defined in claim 3 wherein the filter comprises a phase-only filter determined based on the three-dimensional image.

Claim 6

A method of comparing a three-dimensional facial image with a two-dimensional intensity image of a face as defined in claim 4 wherein the two-dimensional intensity image is transformed according to one of a Fourier transform, binary transform, and non-linear joint transform and the filtered transformed two-dimensional intensity image is transformed according to an inverse of said transform.

Claim 7

A method of comparing a three-dimensional facial image with a two-dimensional intensity image of a face as defined in claim 5 comprising the step of repeating the step of performing a correlation for each of a plurality of different three-dimensional images.

Claim 8

A method of comparing a three-dimensional facial image with a two-dimensional intensity image of a face as defined in claim 1 wherein the two-dimensional intensity image is transformed according to one of a Fourier transform, binary transform, and non-linear joint transform.

Claim 9

A method of comparing a three-dimensional facial image with a two-dimensional intensity image of a face as defined in claim 1 wherein the two-dimensional intensity image comprises pixels, the method comprising the step of normalising pixels within the two-dimensional intensity image.

Claim 10

A method of comparing a three-dimensional facial image with a two-dimensional intensity image of a face as defined in claim 1 wherein the correlation is performed substantially according to the following function: |c|.sup.2 ≅ι.sub.x.sup.2 |p.sub.x (x,y)Xƒ.sup.i.sub.x |.sup.2 +ι.sub.y.sup.2 |p.sub.y (x,y)Xƒ.sup.i.sub.y |.sup.2 +ι.sub.z.sup.2 |p.sub.z (x,yXƒ.sup.i.sub.z |.sup.2.

Claim 13

A system for performing facial recognition according to claim 10 wherein the means for transforming the intensity image comprises means for one of Fourier transform, binary transform, and non-linear joint transform.

Claim 14

A system for performing facial recognition according to claim 10 wherein the means for transforming the filtered transformed intensity image comprises means for performing substantially the inverse transform to that performed by the means for transforming the image.

Claim 15

A system for performing facial recognition according to claim 10 wherein the means for transforming the intensity image comprises Fourier transform means and wherein the means for transforming the filtered transformed intensity image comprises inverse Fourier transform means.

Claim 16

A system for performing facial recognition according to claim 13 wherein the means for transforming the intensity image and the means for transforming the filtered transformed intensity image comprise lenses for performing the transforms on an optical signal.

Claim 17

A system for performing facial recognition according to claim 10 comprising means for determining a phase only filter in dependence upon a known three-dimensional image of a face for use by the means for filtering the transformed image.

Claim 18

A system for performing facial recognition as defined in claim 10 wherein the means for providing a two-dimensional intensity image of a face comprises image capture means for capturing a first intensity image and for providing a first signal in dependence upon the captured image; and, wherein the means for transforming the intensity image, the means for filtering the transformed intensity image, and the means for transforming the filtered transformed intensity image comprise at least a processor for receiving the first signal and for applying a transform to the first signal to provide a transformed first signal, for filtering the transformed first signal, the filter determined in dependence upon a three-dimensional image of a face and for applying an inverse of the transform to the filtered transformed first signal.

Claim 19

A system for performing facial recognition as defined in claim 10 comprising a light source for providing a beam of light; a filter for filtering the beam of light, the filter for receiving a first signal and for filtering in dependence thereon, and wherein the means for providing a two-dimensional intensity image of a face comprises image capture means for capturing a first intensity image and for providing the first signal in dependence thereon; wherein the means for transforming the intensity image in a predetermined fashion comprises a lens for receiving the filtered beam of light and for transforming the beam of light in a predetermined fashion; wherein the means for filtering the transformed intensity image in dependence upon a known three-dimensional image comprises a second filter for filtering the beam of light, the second filter for receiving a second signal in dependence upon a known three-dimensional image and for filtering in dependence thereon; and, wherein the means for transforming the filtered transformed intensity image to produce a result indicative of a correlation between the provided intensity image of a face and the known three-dimensional image comprises a lens for receiving the filtered transformed beam of light and for transforming the beam of light in substantially an inverse fashion to the predetermined fashion.

Claim 20

A system for performing facial recognition as defined in claim 17 wherein the second filter comprises a spatial light modulator.

Claim 21

A system for performing facial recognition as defined in claim 10 wherein the means for providing a two-dimensional intensity image of a face consists of a single two dimensional intensity image capture means.

Claim 24

A method of comparing a three-dimensional facial image with a two-dimensional intensity image of a face as defined in claim 20 wherein the three orthogonal images are used to define a phase-only filter according to P=P.sub.x (x,y)i+P.sub.y (x,y)j+P.sub.z (x,y)k.