Dynamic Range

Cinematographers use "dynamic range" for the luminance range of a scene being captured, or the limits of luminance range that a given digital camera or film can capture.

In the domain of digital imaging, algorithms have been developed to map the image differently in shadow and in highlight in order to better distribute the lighting range across the image. These techniques are known as local tone mapping, and usually involves overcoming the limited dynamic range of the sensor array by selectively combining multiple exposures of the same scene in order to retain detail in light and dark areas. The same approach has been used in chemical photography to capture an extremely wide dynamic range: A three-layer film with each underlying layer at 1/100 the sensitivity of the next higher one has, for example, been used to record nuclear-weapons tests.

In photography, dynamic range is measured in EV differences (known as stops). An increase of one EV, or 'one stop', represents a doubling of the amount of light. Conversely, a decrease of one EV represents a halving of the amount of light. To reveal detail in the darkest shadow requires high exposures. Inversely, to prevent 'bleaching out' of detail in very bright areas, one must choose very low exposures. Most cameras cannot provide this range of exposure values within a single exposure, due to their low dynamic resolution.

 

Dynamic ranges of common devices

DeviceStopsContrast
LCD 9.5 700:1 (250:1 – 1750:1)
Negative film (Kodak VISION3) 13 8000:1
Human eye 10–14 1000:1 – 15000:1
High-end DSLR camera (Nikon D810) 14.8 28500:1

 

 

Also see High-dynamic-range imaging (HDRI or HDR)