Moving picture compression/coding apparatus and motion vector detection method

A motion vector detecting method comprising:

• a motion vector detecting step of detecting a motion vector within a first motion vector detection area from a decoded moving image signal generated by compression-coding a macroblock moving image signal generated by fractionizing an input moving image into a number, N, of units per frame (here, N is a natural number not less than 2) and then, decoding the compression-coded macroblock moving image signal, and from the macroblock moving image signal;
• a motion vector counting step of counting, as the number of first motion vectors, the number of, of the detected motion vectors, motion vectors existing between a first outermost line which is an outermost line of the first motion vector detection area and a second outermost line which is an outermost line of a second motion vector detection area existing inside the first motion vector detection area;
• a motion vector counting step of counting the number of first motion vectors which is the number of motion vectors existing on the first outermost line which is the outermost line of the first motion vector detection area and on one or a plurality of second outermost lines adjoining the first outermost line, said second outermost lines each being the second outermost line which is the outermost line of the second motion vector detection area inside the first motion vector detection area;
• and
• a motion vector detection area determining step of enlarging the first motion vector detection area based on the counted number of first motion vectors.