Preservation of edges: the mechanism for improvements in HDR imaging

There are a number of modern myths about High Dynamic Range (HDR) imaging. There have been claims that multiple-exposure techniques can accurately record scene luminances over a dynamic range of more than a million to one. There are assertions that human appearance tracks the same range. The most common myth is that HDR imaging accurately records and reproduces actual scene radiances. Regardless, there is no doubt that HDR imaging is superior to conventional imaging. We need to understand the basis of HDR image quality improvements. This paper shows that multiple exposure techniques can preserve spatial information, although they cannot record accurate scene luminances. Synthesizing HDR renditions from relative spatial records accounts for improved images.