Device and method of retrieving high-speed motion

A high-speed motion retrieval device comprising:

• an compressive encoding device;
• said compression encoding device including:
• image input means for receiving an image in one frame units;
• motion vector retrieval means for obtaining a correlation between a current frame and a previous frame output from said image input means;
• inter-block differentiating means for performing a differential operation to a block at a location corresponding to a motion vector on a reference frame, said motion vector being a vector to the location where a minimum predictive error has been obtained through retrieval of said motion retrieval means;
• frequency conversion means for converting block differential data obtained by said interblock differentiating means into a frequency component;
• quantization means for quantizing said frequency component;
• and
• variable-length encoding means for compressively encoding a quantized output from said quantization means;
• said motion vector retrieval means including first-stage motion retrieval means and second-stage motion retrieval means;
• wherein said first-stage motion retrieval means retrieves a retrieval range to be decided by referring to a retrieval result in said previous frame, ends a motion retrieval process at the time said range has been retrieved if a predictive error is smaller than a threshold value, retrieves a region not retrieved by said first-stage motion retrieval means within a retrieval range predetermined by said second-stage motion retrieval means if the predictive error is larger than the threshold value, thus obtaining a region with a minimum predictive error, and wherein said first stage motion retrieval means performs retrieval in two steps and dynamically varies a first-stage retrieval range, thus performing motion vector retrieval with less erroneous detection at high speed.