High Dynamic Range (HDR) imaging is a technique levels captured by a digital camera. In image processing, computer graphics, and photography, high dynamic range imaging (HDRI) is a set of techniques that allow a greater dynamic range of luminance between the lightest and darkest areas of an image than current standard digital imaging techniques or photographic methods. This wide dynamic range allows HDR images to more accurately represent the range of intensity levels found in real scenes, ranging from direct sunlight to faint starlight.

The two main sources of HDR imagery are computer renderings and merging of multiple photographs, the latter of which in turn are individually referred to as low-dynamic-range (LDR) or standard-dynamic-range (SDR) photographs. Tone-mapping techniques, which reduce overall contrast to facilitate display of HDR images on devices with lower dynamic range, can be applied to produce images with preserved or exaggerated local contrast for artistic effect.

In photography, dynamic range is measured in Exposure Value (EV) differences (known as stops) between the brightest and darkest parts of the image that show detail. An increase of one EV or one stop is a doubling of the amount of light.

The human eye is capable of viewing scenes with a very large range of light levels. The human eye has over 20 stops of dynamic range, and a typical consumer camera has about 7 stops. High end professional cameras may have as much as 13 stops of dynamic range, but this is still several hundred times less light level range than your eye can see. This is why snapshots taken of breathtaking scenes often look lackluster. This is also why lighting is such an important aspect of photography and cinematography, and why so many scenes in films are taken from a fixed viewpoint (the camera cannot move, otherwise the lighting in the scene gets disrupted).

High-dynamic-range photographs are generally achieved by capturing multiple standard photographs, often using exposure bracketing, and then merging them into an HDR image. Digital photographs are often encoded in a camera’s raw image format, because 8 bit JPEG encoding doesn’t offer enough values to allow fine transitions (and also introduces undesirable effects due to the lossy compression). Some cameras have an auto exposure bracketing (AEB) feature with a far greater dynamic range than others.