A method and apparatus for controlling the execution of image processing operations carried out on an array of image signals, the specific operations having been identified by a plurality of predefined windows. The windows are divided into a plurality of regions, the boundaries of which correspond to transitions from one window region to another. Each region defines an exclusive region within the array of image signals, and the image processing operations to be applied to the signals within the boundaries of that region. The image processing operations are selected by decoding an effect data word that is assigned to each pixel and which follows the pixel along the image processing path. The bits within the effect data word are not assigned individual significance which allows the effect data word, in most cases, to maintain the same bit length even though additional image processing procedures or modules have been added to the image processing path. The apparatus is designed to efficiently manage the identification of regions while minimizing the bit length of the effect data word used to identify the image processing steps. The apparatus also provides flexibility of architecture design resulting in more efficient expansion of functions and easier modifications to existing functions.