Patent ID: 6754397
Filing Date: 2004-06-22
Classification: G06T

Abstract:
A method for designing a filter for scaling an image according to a predetermined ratio, comprising:designing a template Finite Impulse Response (FIR) filter for scaling an image according to the predetermined ratio having template coefficients that are real numbers; designing an ideal filter from the FIR template filter; filtering a sample image with the ideal filter to derive a reference image; determining a scalable skeleton filter having integer coefficients derivable from the template coefficients and conforming to an integer normalization requirement within a first preset tolerance; selecting a coefficient domain having a finite plurality of integer values for varying at least one of the integer coefficients of the skeleton filter to derive a finite universe of available integer coefficient sets around the skeleton integer filter; selecting all integer coefficient sets available in the universe, thereby deriving a plurality of available corresponding test filters; approving only the available test filters that perform well in terms of preset filter performance parameters; filtering the sample image with each of the approved test filters to yield respective test images; comparing each of the test images with the reference image to determine respective sets of metrics for predicted visually perceptible differences from the reference image; ranking the test filters according to how well their respective sets of metrics meet preset visual difference evaluation criteria; and choosing the top ranked test filter.