Patent ID: 7064770

Claim:
A digital signal processing method for optimized hardware and software implementation of single-pass digital image resampling with an anisotropic filter to transform a two-dimensional video input image having an input pixel coordinate space and input digital pixel data, into an output image having an output pixel coordinate space and output digital pixel data, said method comprising: (a) obtaining two-dimensional video input digital image data for an output pixel; (b) mapping the output pixel coordinates onto the input image coordinate space to determine a mapped coordinate position; (c) determining the Jacobian matrix of the output pixel coordinates with respect to the input coordinates at the mapped coordinate position determined in (b); (d) determining major and minor radii and the orientation of the major radius to uniquely determine an ellipse around the mapped coordinate position determined in (b), formed by two row vectors of the determined Jacobian matrix in (c); (e) extending and adjusting the radii of said ellipse based on a required image quality and a required processing speed; (f) determining a footprint based on the result of (e) in the input image coordinate space around said mapped coordinate position determined in (b), to include input pixels participating in the filtering; (g) transforming the ellipse of (d) into a circle having a radius of one unit to facilitate distance calculation of the included input pixels from the center of the circle; (h) determining coefficients of the anisotropic filter for all input pixels in the footprint from a circularly symmetric profile as a function of the distance in (g); (i) determining the value of the output pixel by accumulating values of the input pixels inside the footprint with coefficients determined in (h); and saving the value of the output pixel.