Abstract: A image processing apparatus receives two video signals representing different video images. Included in the processor are a number of dual ported memories, each capable of storing a field of the video images. A designation is provided as to whether the images contain a single field or two interlaced fields per image and which of the memories is to store each field. The processor is designed so that both video images can be simultaneously received and stored in the memories. Once a predesignated amount of the received video images have been stored, selected portions of the image data can be read from the memories for processing before the entire image has been stored. The two video images also can be received at different times, in which case the processor halts any image processing which is occurring in order to acquire and store a later image. The processing is performed on the pixels of the image that lie within a user defined window.