1. A method of processing an array of image data, comprising: applying a predefined family of transform filters to the array of image data so as to generate successive sets of transform coefficients, each set of transform coefficients including edge coefficients at outside boundaries of the set of transform coefficients and non-edge coefficients positioned at interior locations of the set of transform coefficients; the sets of transform coefficients including a last set of transform coefficients and one or more earlier sets of transform coefficients; and the applying including applying a short transform filter to image data at boundaries of the array and to coefficients positioned at boundaries of each earlier set of transform coefficients so as to generate the edge coefficients, and applying a long filter to image data at interior locations of the array and to coefficients at interior locations of the earlier sets of transform coefficients so as to generate the non-edge coefficients; wherein the short transform filter has a shorter filter support than the long transform filter, and both the short transform filter and the long transform filter are applied only to image data within the array and only to transform coefficients within the earlier sets of transform coefficients for the array while generating the sets of transform coefficients.