A fast algorithm for orthogonalizing polynomials on an arbitrarily shaped region (revised version)

Segmented image coding segments an image into non-rectangular regions and approximates the texture in each region by a weighted sum of orthonormal base functions. These orthonormal base functions, which are region-specific, used to be generated by the Gram-Schmidt (GS) algorithm, which is unfortunately very time-consuming. This paper presents the polynomial recursive orthogonalization (PRO) algorithm which generates the same orthonormal base functions as GS, but which is faster than GS because it is based on a recurrence which has fewer terms than the corresponding GS equation. The paper presents theoretical and experimental results which show that PRO is two to three times faster in practice (depending on the number of computed base functions).