1. A method comprising: receiving a higher dynamic range image; generating, from said higher dynamic range image, a lower dynamic range image and an exposure map allowing the higher dynamic range image to be reconstructed from the lower dynamic range image, wherein said exposure map includes a multiplier for each pixel of said lower dynamic range image; imposing a smoothing constraint on said exposure map to generate a smoothed exposure map; encoding the lower dynamic range image; encoding the smoothed exposure map; and, transmitting said lower dynamic range image and said smoothed exposure map.