High-dynamic-range imaging (HDR) aims at producing images with a similar luminance range as that experienced through human sight. To achieve this extended luminosity range both in photo and in video, a camera system reaches beyond its native capabilities, relying on post-processing techniques such as capturing and merging images taken at different exposure levels.
Display contrast and printing limitations may make it necessary for the extended luminosity range achieved by high-dynamic-range imaging to be compressed, in a process known as tone mapping. This technique works by approximating the image to the displayable range while preserving details and color.
The roots of high-dynamic-range imaging trace back at least to the mid 19th century, when French photographer Jean-Baptiste Gustave Le Gray experimented with different exposures. Since then, analog and digital tone mapping and other related techniques have been intensely explored, and HDR has become a common feature in current cameras. HDR has also become a common smartphone camera feature for most current models, except for some budget products and feature phones.