High dynamic range (or HDR for short) is a term generally used for media applications such as digital imaging and digital audio production. It is a feature that is capable of producing a much higher dynamic range than is widely available at the moment.

Applications in digital imaging:

Applications in digital audio production

Dynamic range, abbreviated DR or DNR, is the ratio between the largest and smallest possible values of a changeable quantity, such as in signals like sound and light. It is measured as a ratio, or as a base-10 (decibel) or base-2 (doublings, bits or stops) logarithmic value.

The human senses of sight and hearing have a very high dynamic range. A human is capable of hearing (and usefully discerning) anything from a quiet murmur in a soundproofed room to the sound of the loudest heavy metal concert. Such a difference can exceed 100 dB which represents a factor of 100,000 in amplitude and a factor 10,000,000,000 in power. A human can see objects in starlight (although colour differentiation is reduced at low light levels) or in bright sunlight, even though on a moonless night objects receive 1/1,000,000,000 of the illumination they would on a bright sunny day: that is a dynamic range of 90 dB.^{[citation needed]} A human cannot perform these feats of perception at both extremes of the scale at the same time. The eyes take time to adjust to different light levels and the dynamic range of the human eye in a given scene is actually quite limited due to optical glare. The instantaneous dynamic range of human audio perception is similarly subject to masking, so that, for example, a whisper cannot be heard in loud surroundings. Nevertheless, a high-quality audio reproduction system should be able to reproduce accurately both the quiet sounds and the loud; similarly, a high-quality camera system should be able to capture both shadow details in nighttime scenes and bright areas of sunny scenes.