| 摘要 |
A method and system for circularly symmetric anisotropic filtering over an extended elliptical or rectangular footprint in singlepass 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 theinput image.
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