Abstract: A flash unit comprising a flash light source (2) and a projector lens (8) positioned to project light from the flash source onto a subject. In a preferred embodiment there are two flash light sources for projecting patterned and unpatterned light respectively on to the subject, and a circuit is provided to trigger the two flash sources with a predetermined time interval therebetween.

Abstract: A method of compressing an image frame composed of an array of pixels in the form of digital electrical signals, the method comprising the steps of: (a) providing a reference image as a first approximation to the original image to be compressed; (b) dividing the original image into patches of one or more sizes; (c) for each patch determining a compressed encoding of the data contained therein where the compressed encoding can be uncompressed to provide an approximation to the patch; (d) selecting that one of the compressed encodings which, when uncompressed and added to the reference image, gives the biggest improvement therein relative to the original image; (e) adding the selected compressed encoding in uncompressed form to the reference image and in compressed form to a compressed representation of the original image; and (f) recursively repeating step (d) for the remaining compressed encodings until either a desired quality level of the reference image or a maximum data size of the compressed representati