Method for block matching motion estimation in digital video sequences

A digital video sequence encoder:

• a displacement encoder (2) having a first input for connection to a current frame signal source;
• a reference frame storage circuit (3) having an output connected to a second input of said displacement encoder;
• and
• a motion compensated predictor circuit (7) having an input connected to an output of said displacement encoder,
• said first input for accepting a first input signal representing a current image frame from the current frame signal source,
• said second input for accepting a signal representing a reference image frame from said reference frame storage circuit,
• the displacement encoder configured for
• dividing the current image frame and the reference image frame each into plural blocks of a rectangular shape,
• for the plural blocks of the current image frame, searching the reference frame for corresponding blocks,
• calculating a motion vector representing a position difference between each of the plural blocks and the corresponding blocks of the reference frame,
• determining a mean motion vector for one block of the reference frame,
• establishing a search window based on a horizontal displacement and a vertical displacement of the one block,
• from the motion vector calculating step, determining a mean absolute difference of the motion vector of the one block,
• determining a target probability of finding a minimum of the mean absolute difference searching within the search window and outside the search window,
• determining whether the minimum of the mean absolute difference is within the search window or outside the search window, and
• locating the minimum of the means absolute difference and outputting at the output of the displacement encoder a displacement estimation signal to the input of the motion compensated predictor circuit.