1. A method of processing an image in an image processor, comprising the steps of: receiving input samples representing a spatially sampled attribute of an image having a width or height of N sample pitches; representing said image by N+1 rows or columns respectively of samples so that opposite image edges lie on sample positions; providing a symmetrical resampling filter having a plurality of filter-inputs defining a filter aperture and a filter-output and configured to take contributions from some or all of the filter-inputs to provide the filter-output; and resampling said samples with said resampling filter to provide output samples, in which the aperture extends beyond a said image edge for some output samples; wherein contributions to said resampling filter from positions outside the image are obtained by copying values from positions inside the image and wherein the said positions inside the image and the respective said positions outside the image are equidistant from an image edge; wherein the value of an image-edge sample input to a resampling filter is derived from the values of neighbouring input samples falling within the aperture of that resampling filter; and wherein the value of an image-edge sample input to a resampling filter is determined from a required ratio of the value of the said input sample value to the value of the corresponding co-located filter output sample.