What is the Unit of Dynamic Range?
Dynamic range is a ratio and as such, a dimensionless quantity. In photography and imaging, the dynamic range represents the ratio of two luminance values, with the luminance expressed in candelas per square meter. The range of luminance which human vision can handle is quite large. While the luminance of starlight is around 0.001 cd/m2, that of a sunlit scene is around 100,000 cd/m2, which is a hundred million times higher. The luminance of the sun itself is approximately 1,000,000,000 cd/m2. The human eye can accommodate a dynamic range of approximately 10,000:1 in a single view. A scene showing the interior of a room with a sunlit view outside the window, for instance, will have a dynamic range of approximately 100,000:1.
