Programming languages for compressing graphics

Abstract

Images are programs. They are usually simple instructions toa very specialized interpreter that renders them on screen. Image formats therefore correspond to different programming languages, each with distinctive properties of program size and accuracy. Image-processing language srender large images from small pieces of code.We present Evolver,a language and toolkit that perform the reverse transformation.The toolkit accepts images in conventional graphics formats like JPEGand uses genetic algorithms to grow a program in the Evolver language that generates a similar image. Because the program it produces is of ten significantly smaller than the input image, Evolver can be used as acompression tool.The language balances the tradeoff between having many features, which improves compression, and fewer features, which improves searching. Inaddition, by being programmatic descriptions, the rendered images scalemuch better to multiple resolutions than fixed-size images. We have implementedthis system and present examples of its use.