Optical Flow Approximation of Sub-Pixel Accurate Block Matching for Video Coding

Video compression algorithms almost universally rely on block matching algorithms (BMA) to exploit the temporal redundancy in image sequences. However block matching is extremely computationally intensive, especially if sub-pixel accuracy is desired. We propose a fundamentally different approach to obtaining motion vectors using the principles from gradient based optical flow but in a form fully compatible with any macro-block based video compression scheme. Experimental results show that in many cases, the gradient approximation to block matching results in videos within 0.3 dB PSNR to BMA at sub-pixel resolution while being potentially much more computationally efficient and easier to implement at the hardware level.