A directional & adaptive diamond search by adaptive pattern switching with a predicted motion vector

We propose a simple fast block-matching algorithm (BMA) based on the direction of the predicted motion vector called directional & adaptive diamond search by adaptive pattern switching (DADS-APS). The proposal method has two sequential search steps, including 1) an initial search, and 2) a refinement search for the local area. Adaptive pattern switching (APS) is proposed for the initial search and a unit-size rood pattern is used for the refinement. The initial search step consists of pattern size determination and selection of a pattern shape. We use an adaptive pattern size that is adjusted by the amount of motion. This method is superior to a fixed-pattern size algorithm, regardless of the amount of motion. In video sequences, each motion has a unique direction. Using this property, we use adaptive pattern switching between ARPS and DADS. APS considers the motion direction so we can easily and correctly find the minimal matching error (MME) point with less error distortion. APS can thus reduce the number of poorly related search points. Analysis shows that DADS-APS exhibits good PSNR performance and the average number of search points compares favorably with other methods.