Motion estimation methods for overlapped block motion compensation.

An extension of conventional block motion compensation (BMC), overlapped block motion compensation (OBMC) has been shown to reduce residual errors and blocking effects in motion-compensated video. However, the overlap creates a noncausal spatial dependence between blocks and complicates motion estimation (ME) for OBMC. Iterative methods have traditionally been employed for overlapped block motion estimation (OBME). For compression, the rate for the motion vector field (MVF) may also be constrained. This work considers several rate-constrained OBME algorithms, both iterative and noniterative. Experiments demonstrate that a simple raster-scan algorithm is effective as a suboptimal, noniterative solution, with comparable or better rate-distortion performance and computational complexity than iterative OBME algorithms. Depending on the application, either this method or a simple block-matching algorithm plus iteration are the most attractive of the tested OBME schemes.