We present a methodology aimed at prototyping real-time image processing VLSI systems. The prototyping methodology includes the emulation of the application in its target environment (i.e. in real time and on real-world scenes) and the automatic derivation of a VLSI chipset implementing the application. Our methodology is based on a custom emulator called the Data-Flow Functional Computer (DFFC) which is dedicated to real-time image processing. Our method encompasses in a coherent environment: 1) the validation of the high-level specification, 2) the simultaneous validation of an implementation of the design suitable for integration and 3) a method for integrating the validated emulator architecture as a VLSI system. We present the results of the successful prototyping and integration of a defect detector algorithm.