1. A method carried out by an electronic data processor, comprising: calculating motion vectors for blocks of pixels in a target image; applying a high pass filter to the calculated motion vectors to determine a variance of the calculated motion vectors; generating a search range associated with a target block of pixels in the target image using the variance of the calculated motion vectors; calculating a safety margin for the search range based on motion vectors of at least one preceding neighboring block of pixels; expanding the search range using the safety margin; and using the generated search range to estimate motion of the target block of pixels.