Abstract: A method and apparatus for image scaling of continuous tone images to be rasterized and output to a recording or imaging device using incremental interpolation. The method employs multiple parallel interpolators, each of which contains an accumulation sum to which an accumulation constant is added. When each accumulation sum exceeds a reference value, a transition event is signaled, to be used for selection of contone image data value for processing. By initially loading the accumulation sums with shifted data and employing interpolation logic, multiple transition events can be calculated within one output resolution processing cycle.