In a computer implemented method of creating a collage of images, a first
image is seeded into a viewing region to start the collage. A plurality
of trial layout arrangements are provided with an additional image added
to the collage. An occlusion cost is generated for a trial layout
arrangement. The occlusion cost represents image saliency occluded and
viewing region saliency occluded by the trial arrangement. An image is
added to the collage, by updating the collage to reflect one of the trial
layout arrangements for which the occlusion cost has been generated.