1. A method of compressing images generated on an image generating device, the method comprising: responsive to a generated image and position and orientation data associated with an image generating device which generated the image, selecting a previously generated image having a similar position and a similar orientation as the generated image; comparing the selected previously generated image with the generated image; and if the comparison between the selected previously generated image and the generated image indicates a difference between the selected previously generated image and the generated image is less than a threshold difference, then compressing the generated image using the selected previously generated image.