motioncompensation

Motion compensation is a technique used in signal processing, particularly in video compression and image processing, to reduce redundancy by exploiting the temporal correlation between consecutive frames. The core idea is that large portions of a scene often remain unchanged or move predictably between frames. Instead of encoding each frame independently, motion compensation aims to represent these unchanged or moving regions more efficiently.

This is typically achieved by dividing a frame into blocks and searching for corresponding blocks in a reference frame. Once a match is found, the encoder only needs to transmit the motion vector, which indicates the displacement of the block from its position in the reference frame, along with any difference (residual) between the current block and the predicted block. The decoder then uses the motion vector and the reference frame to reconstruct the current block.

Motion compensation significantly improves compression ratios by reducing the amount of data that needs to be transmitted or stored. It is a fundamental component of modern video codecs such as H.264 (AVC) and H.265 (HEVC). There are various methods for motion estimation, including block matching algorithms like Full Search, Three-Step Search, and Hexagonal Search, each offering different trade-offs between accuracy and computational complexity. The effectiveness of motion compensation is crucial for achieving high-quality video at low bitrates.