Gradient domain HDR compositing

High dynamic range (HDR) image compositing addresses dynamic range limitations by combining valid information from multiple differently-exposed low dynamic range (LDR) images. Traditional HDR methods (which we will call intensity-based) compute a weighted combination of pixel irradiance after correcting for differences in exposure. These methods require knowledge of the mapping from scene irradiance to image brightness called the camera response function f, as well as the exposure settings (combined information about shutter speed and film sensitivity), k. However, often times neither f nor k are available beforehand; most digital cameras do not have the option to shoot in raw (linear) mode, and do not offer a guarantee that the same processing will be performed on consecutive images.