Methods and systems for enhanced dynamic range images and video from multiple exposures
Aspects of the present invention relate to systems and methods for video coding and decoding. Some aspects relate to coding and decoding of enhanced dynamic range video sequences based on a series of low-dynamic-range (LDR) frames, captured at a first exposure configuration, that are multi-plexed with a series of enhancement frames that are captured at a second exposure configuration.
1. A method for generating an enhanced dynamic range (EDR) image frame from a low dynamic range (LDR) image frame and a plurality of enhancement frames, said method comprising:
a) computing a Laplacian pyramid for each of said enhancement frames and said LDR image frame, each said Laplacian pyramid computed based on an adaptive Gaussian pyramid;
b) computing blend pyramids corresponding to said enhancement frame pyramids, said blend pyramids denoting how pixels in said enhancement frame pyramids are to be used in a pyramid blending process, said blend pyramids computed by: (i) computing initial blend pyramids using temporal weights respectively assigned to said enhancement frames; and (ii) modifying said initial blend pyramids using maps of mis-match values between pixels of said enhancement frames and respective reference frames; and
c) performing pixel-wise maximization between said Laplacian pyramids according to said blend pyramids, thereby creating a blended pyramid.
2. A method as described in claim 1 wherein said blend pyramids comprise weighting factors that define a relative contribution of pixels in said enhancement frame pyramids during said performing.
3. A method as described in claim 1 further comprising assigning temporal weight values to said enhancement frame pyramids.
4. A method as described in claim 1 further comprising performing a binary thresholding operation on said blend pyramids.
5. A method as described in claim 1 further comprising performing a smoothing operation on said blend pyramids.