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I understand that dynamic range is the difference between the brightest and darkest lighting, but why dynamic? Why not static range?

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Jossie Calderon is a new contributor to this site. Take care in asking for clarification, commenting, and answering. Check out our Code of Conduct.
30

Because "dynamic range" does not refer to a range that is dynamic, but rather to a range of dynamics. For example: range of luminosities or reflectances in photography, or a range of amplitudes in acoustics.

Note that "dynamic" comes from Greek δύναμις meaning "power".

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    Yes. The term originated in audio engineering and spread to other fields from there. The relation to "dynamics" in music is entirely intended. – hobbs 19 hours ago
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    @hobbs: Especially considering that light, like sound, takes the form of waves that have measurable amplitude. – supercat 10 hours ago
  • Note that unlike range, dynamic contrast ratio vs static contrast ratio (where "dynamic" and "static" are adjectives) is very much a thing when discussing capabilities of monitors. – Ruslan 8 hours ago
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It's not the difference, it's the ratio.

A ratio does not have a fixed 'bottom' or 'top', therefore is dynamic rather than static.

Ref: Wikipedia - Dynamic Range

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    To be fair, since DR is usually expressed in logarithms, the logarithm of a ratio is the same as the difference of the logarithms of the parts of the ratio. /nitpick. =) – scottbb 23 hours ago
  • You sure? The answer below me says different and sounds more persuasive. – Jossie Calderon 23 hours ago
  • @JossieCalderon which answer are you referring to? (hint, you can click the little 'share' text and copy/paste the actual link the answer, which is not ambiguous) – UuDdLrLrSs 1 hour ago
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Seemingly-constant illumination in fact represents a mixture of high-frequency waves. If the intensity is low enough, and one exposes a piece of film, these waves will cause a sequence of randomly-distributed changes to the states of the crystals in the emulsion. While some kinds of detection apparatus may seem to regard light as a steady state, what actually happens within the apparatus is that light will knock something in the apparatus out of its rest state, then the apparatus will reset it, then light will knock it again, etc. The processes associated with light are generally so fast that, by the law of large numbers, they appear uniform, but underneath that apparent uniformity things are in fact constantly changing.

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Multiple frames are captured and extra information (as in more lighting) is added to some frames and reduced in others. The frames are then combined into one to amplify the bright and dark colors. This gives you a high range of saturation which can be changed, so that's why the HDR stands for High Dynamic Range.

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Jossie Calderon is a new contributor to this site. Take care in asking for clarification, commenting, and answering. Check out our Code of Conduct.
  • 7
    I'm confused, you answer your own question, but your answer is only about high dynamic range and not about why it's called dynamic range. Your answer does not really fit to your question. – Matt yesterday
  • @Matt: Within the about is the why. I literally say why it's called HDR. – Jossie Calderon 2 hours ago

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