1. A method for processing image data during a single pass through an image, comprising the following steps: a) loading a next scanline of image data into a first-in-first-out rolling band buffer after the buffer is full; b) performing windowing on the image data in the buffer to generate windows and classify windows according to an image type class; c) determining if a class change was experienced by any window in the output scanline of the buffer during traverse of the scanline from the input of the buffer to the output of the buffer; d) if a class change was experienced for a window in the output scanline of the buffer, processing image data in the output scanline for that window using a blended rendering algorithm; and e) if a class change was not experienced for a window in the output scanline of the buffer, processing image data in the output scanline for that window using a class-based rendering algorithm associated with the image type class for the window.