COMPUTER GRAPHICS

A method for producing an image of a scene including a refractive object includes generating an illumination map, representing the scene. The method creates a first bitmap for the refractive object, the bitmap comprising a plurality of pixels; each of said pixels in the first bitmap is mapped to a pixel in a second bitmap, the mapping representing the effect of refraction on light passing through the object; and the effects of the light illuminating the pixels in the first bitmap are added into said second bitmap.