1. A method of selecting a plurality of patches within a region of a page, for use in image alignment, said method comprising: determining one or more candidate image alignment patches distributed across a region of the page, based on content in the page region, each candidate patch being associated with a feature strength value; applying a distribution of grid nodes to the page region, at least one attribute of the distribution of grid nodes being dynamically adjusted according to the distribution of the candidate patches across the page region; and selecting a corresponding patch from the distribution of candidate patches for each of a plurality of the grid nodes, wherein each of the selected patches is selected based on proximity of the selected patch to a corresponding grid node.