Spatially adaptive filtering for registration artifact removal in HDR video

One method to extend the dynamic range of video captured with inexpensive cameras is to alternate the exposure time between frames and combine the information in adjacent frames using post-processing. This method requires no hardware modification, yet traditionally there is a quality tradeoff. Dynamic range expansion corresponds to an increased number of saturated pixels in individual frames, which along with occlusions contributes to registration artifacts. Therefore, we describe a “High Dynamic Range (HDR) Filter” that can mitigate these artifacts to produce a pleasing HDR video without exact frame registration. This filter builds upon the bilateral filter to smooth frames while maintaining important edges. Additionally, the filter strength locally adapts to corresponding motion vectors. Since regions with poor registration generally correspond to higher motion, smoothing here can reduce artifacts without degrading perceptual quality. Results show a significant improvement for HDR videos with fast local motion within saturated regions.