US Patent 9361679 Temporally coherent local tone mapping of HDR video

Approaches are described for filtering a first image frame in a sequence of image frames. A tone-mapping pipeline applies a spatiotemporal filter to each pixel of the first image frame, based on a forward optical flow and a backward optical flow, to produce a base layer image. The tone-mapping pipeline applies a temporal filter to each pixel of the first image frame, based on the forward optical flow and the backward optical flow, to produce a temporally filtered frame. The tone-mapping pipeline produces a detail layer image based on the base layer image and the temporally filtered frame.