1. An image property detection apparatus for processing a pair of images representing different respective views of a scene to generate a colour property difference amount, the apparatus comprising: a difference detector configured to derive a difference amount dependent upon an average of differences in colour properties between the pair of images at each of a set of possible image colours, each of the set of possible image colours being weighted by image content of at least one of the pair of images at that respective image colour; an area selector configured to select an area of the image over which a histogram is to be calculated, such that the area is divided into pixel value bins; and a noise adder configured to add a noise signal to an output signal of the area selector such that pixels that are adjacent to a boundary of two bins are randomly placed into the bins on either side of the boundary.