Segmentation of Rectangular Objects Lying on an Unknown Background in a Small Preview Scan Image

We describe a method to segment rectangular objects that lie on a slightly textured background of an a-priori unknown colour. Our contribution consists of a fast and accurate background colour approximation method, a set of heuristics for accurate detection of rectangle sides, and procedures to generate imprecise hypotheses of rectangles, adjust hypotheses to fit the rectangles in the image, and verify or reject the hypotheses. Our algorithm is capable of detecting overlapping and touching objects such as photos, receipts, and business cards on a very small-sized preview scan image (79 by 109 pixels) on a coloured/textured background.