Patent ID: 7577309

Claim:
A method of determining a focused image f(x,y) of a scene with respect to a camera, said scene having a 3D shape z(x,y) which is characterized by a shape parameter vector z, and said camera characterized by a set of camera parameters e p , said method comprising: (a) recording a set of images g p (x,y) of said object with different camera parameter settings e p , for p=1,2,3, . . . ,P; (b) obtaining a set of normalized images by preprocessing said set of images g p (x,y) to reduce noise by filtering and normalizing them with respect to average brightness and magnification so that said set of normalized images are related to said focused image f(x,y) by a linear integral of the product of said focused image with a non-localized shift-variant point spread function h′; (c) computing a set of derivatives g p (m,n) (x,y) of said set of normalized images to obtain a set of image derivatives where m and n are the integer order of derivatives with respect to x and y respectively, for m,n=0,1,2,3, . . . ; (d) determining the localized shift-variant point spread function (SV-PSF) h from said non-localized PSF h′ using the novel Rao Localization Transform expressed in the form h ( x,y,α,β;e p ,z )= h′ ( x+α,y+β,x,y;e p ,z ) where (x,y) specifies the position where image brightness is measured and (α,β) specifies the position of surrounding image points which are contributing to light measured at (x,y); (e) deriving a set of expressions for the various moments with respect to α and β of the derivatives with respect to x and y of the localized SV-PSF h i,j (m,n) in terms of the camera parameters e p and shape parameter vector z; (f) deriving a system of P algebraic equations that express said focused image f(x,y) as a weighted sum of the derivatives of said set of normalized images g p (m,n) (x,y) in terms of the Inverse Rao Transform (IRT) coefficients that are functions of h i,j (m,n) ; (g) solving said system of P algebraic equations to obtain said focused image f(x,y) at each point (x,y), and providing it as digital image output.