Patent ID: 7391933

Claim:
A method of interpolating image positions in an original image to produce an interpolated output image, wherein the original image is represented by digital input pixel data, comprising the steps of: (a) providing a first filter having a sharp interpolation characteristic; (b) providing a second filter having a smooth interpolation characteristic; (c) interpolating a selected image position in the image using the first filter to generate a sharp interpolation output value; (d) interpolating the selected image position in the image using the second filter to generate a smooth interpolation output value; (e) calculating a different weighting coefficient for the output of each filter by estimating a high frequency level at the interpolated selected image position and calculating the weighting coefficients based on the estimated image high frequency level; and (f) selectively combining the output values from the filters as a function of the weighting coefficients, to generate an interpolation output value for the selected image position of an interpolated output image, wherein the weighting coefficient α for the first filter output is calculated according to the relation: α=min(1, max(0,(φ− T 1 )/( T 2 −T 1 ))) where φ is the image high frequency level estimated for the given interpolation position, T 1 and T 2 are pre-determined threshold values where T 2 >T 1 ≧0; and the weighting coefficient for the second filter output is (1−α).