Recovering High Dynamic Range Radiance Maps from Photographs Revisited: A Simple and Important Fix
An influential technique introduced by Debevec and Malik has become the de facto standard for recovering high dynamic range radiance maps from photographs and has been widely used in research and commercial systems for over a decade. However, we have discovered an important defect in the original algorithm that will make this technique often fail to produce reasonable results in the extremely bright or dark regions of a scene. In this paper, we introduce a novel technique to correct this defect. Instead of the original algorithm where only pixel values from the photographs are used to guide the synthesis of the high dynamic range radiance map, we explicitly incorporate the shutter speed information of the camera. At each spatial pixel location, we estimate a "suitable shutter" that will make that location best exposed. A pixel's contribution to the high dynamic range radiance value is not only a function of its value but also depends on the difference between shutter speed used to take the pixel and the estimated "suitable shutter" of that pixel. We also show that this new idea can be successfully used to directly fuse differently exposed photographs into a single low dynamic range image for display in conventional low dynamic range devices.