Efficient Image Manipulation via Run-time Compilation

An image manipulation system can be thought of as a domain-specific programming language: by composing and manipulating pictures, the user builds up an expression in such a programming language. Each time the picture is displayed, the expression is evaluated. To gain the required efficiency of display, the expression must be optimized and compiled on the fly. This paper introduces a small language that could form the basis of an image manipulation system, and it describes a preliminary implementation. To compile an expression in the language, we inline all function definitions and use algebraic laws of the primitive operations to optimize composites. We apply a form of code motion to recover (as far as possible) the sharing lost in the inlining phase. Finally, we generate intermediate code that is passed to a JIT compiler.