Mid-19th century The idea of using several exposures to adequately reproduce a too-extreme range of
luminance was pioneered as early as the 1850s by
Gustave Le Gray to render seascapes showing both the sky and the sea. Such rendering was impossible at the time using standard methods, as the luminosity range was too extreme. Le Gray used one negative for the sky, and another one with a longer exposure for the sea, and combined the two into one picture in positive.
Mid-20th century Manual tone mapping was accomplished by
dodging and burning – selectively increasing or decreasing the exposure of regions of the photograph to yield better tonality reproduction. This was effective because the dynamic range of the negative is significantly higher than would be available on the finished positive paper print when that is exposed via the negative in a uniform manner. An excellent example is the photograph
Schweitzer at the Lamp by
W. Eugene Smith, from his 1954
photo essay A Man of Mercy on
Albert Schweitzer and his humanitarian work in French Equatorial Africa. The image took five days to reproduce the tonal range of the scene, which ranges from a bright lamp (relative to the scene) to a dark shadow. With the advent of color photography, tone mapping in the darkroom was no longer possible due to the specific timing needed during the developing process of color film. Photographers looked to film manufacturers to design new film stocks with improved response, or continued to shoot in black and white to use tone mapping methods. extended exposure response film. One can note that each curve has a
sigmoidal shape and follows a
hyperbolic tangent, or a
logistic function characterized by an induction period (initiation), a quasi-linear propagation, and a saturation plateau (
asymptote). Color film capable of directly recording high-dynamic-range images was developed by
Charles Wyckoff and
EG&G "in the course of a contract with the
Department of the Air Force". This XR film had three
emulsion layers, an upper layer having an
ASA speed rating of 400, a middle layer with an intermediate rating, and a lower layer with an ASA rating of 0.004. The film was processed in a manner similar to
color films, and each layer produced a different color. The dynamic range of this extended range film has been estimated as 1:108. It has been used to photograph nuclear explosions, for astronomical photography, for spectrographic research, and for medical imaging. Wyckoff's detailed pictures of nuclear explosions appeared on the cover of
Life magazine in the mid-1950s.
Late 20th century Georges Cornuéjols and licensees of his patents (Brdi, Hymatom) introduced the principle of HDR video image, in 1986, by interposing a matricial LCD screen in front of the camera's image sensor, increasing the sensors dynamic by five stops. The concept of neighborhood tone mapping was applied to video cameras in 1988 by a group from the
Technion in Israel, led by Oliver Hilsenrath and Yehoshua Y. Zeevi. Technion researchers filed for a patent on this concept in 1991, and several related patents in 1992 and 1993. In February and April 1990, Georges Cornuéjols introduced the first real-time HDR camera that combined two images captured successively by a sensor or simultaneously by two sensors of the camera. This process is known as
bracketing used for a video stream. In 1991, the first commercial video camera was introduced that performed real-time capturing of multiple images with different exposures, and producing an HDR video image, by Hymatom, licensee of Georges Cornuéjols. Also in 1991, Georges Cornuéjols introduced the HDR+ image principle by non-linear accumulation of images to increase the sensitivity of the camera: resulting in a mathematical theory of differently exposed pictures of the same subject matter that was published in 1995 by
Steve Mann and
Rosalind Picard. On October 28, 1998, Ben Sarao created one of the first nighttime HDR+G (high dynamic range + graphic) image of
STS-95 on the launch pad at
NASA's
Kennedy Space Center. It consisted of four film images of the
space shuttle at night that were
digitally composited with additional digital graphic elements. The image was first exhibited at
NASA Headquarters Great Hall, Washington DC, in 1999 and then published in
Hasselblad Forum. The advent of consumer digital cameras produced a new demand for HDR imaging to improve the light response of digital camera sensors, which had a much smaller dynamic range than film.
Steve Mann developed and patented the global-HDR method for producing digital images having extended dynamic range at the
MIT Media Lab. Mann's method involved a two-step procedure: First, generate one floating point image array by global-only image operations (operations that affect all pixels identically, without regard to their local neighborhoods). Second, convert this image array, using local neighborhood processing (tone-remapping, etc.), into an HDR image. The image array generated by the first step of Mann's process is called a
lightspace image,
lightspace picture, or
radiance map. Another benefit of global-HDR imaging is that it provides access to the intermediate light or radiance map, which has been used for
computer vision, and other
image processing operations. In the early 2000s, several scholarly research efforts used consumer-grade sensors and cameras. A few companies such as
RED and
Arri have been developing digital sensors capable of a higher dynamic range. RED EPIC-X can capture time-sequential HDRx images With the advent of low-cost consumer digital cameras, many amateurs began posting tone-mapped HDR
time-lapse videos on the Internet, essentially a sequence of still photographs in quick succession. In 2010, the independent studio Soviet Montage produced an example of HDR video from disparately exposed video streams using a
beam splitter and consumer grade HD video cameras. Similar methods have been described in the academic literature in 2001 and 2007. In 2005,
Adobe Systems introduced several new features in
Photoshop CS2 including
Merge to HDR, 32 bit floating point image support, and HDR tone mapping. On June 30, 2016,
Microsoft added support for the digital compositing of HDR images to
Windows 10 using the
Universal Windows Platform. == See also ==