1. A controller for enhancing dynamic range of a first image, the controller configured to: identify one or more enhancement regions within the first image for which luminance values satisfy an enhancement criterion; apply a smoothly-varying brightness enhancement function to the first image to obtain a second image having a dynamic range greater than that of the first image, the brightness enhancement function increasing luminance values of the second image over the first image in the enhancement regions and in at least some areas adjacent to the enhancement regions, the effect of the brightness enhancement function dropping off smoothly with increasing distance from the enhancement regions, wherein the controller is configured to apply the brightness enhancement function to the first image for pixels in the first image by multiplying a corresponding first image pixel value by a corresponding brightness enhancement factor.