A method and system for circularly symmetric anisotropic filtering over an
extended elliptical or rectangular footprint in single-pass digital image
warping are disclosed. The filtering is performed by first finding and
adjusting an ellipse that approximates a non-uniform image scaling
function in a mapped position of an output pixel in the input image
space. A linear transformation from this ellipse to a unit circle in the
output image space is determined to calculate input pixel radii inside
the footprint and corresponding filter coefficient as a function of the
radius. The shape of the footprint is determined as a trade-off between
image quality and processing speed. In one implementation, profiles of
smoothing and warping components are combined to produce sharper or
detail enhanced output image. The method and system of the invention
produce natural output image without jagging artifacts, while maintaining
or enhancing the sharpness of the input image.