(1) The difference between, or ratio, of the highest and lowest signal in an electronic circuit. It measures the highest voltage, current or power compared to the lowest signal. When the music CD first came out in the mid-1980s, its dynamic range was widely touted. The CD could more accurately record an orchestra's range of volume than a vinyl phonograph record, such as from the quietest passages to the loudest drums.
(2) The difference between, or ratio, of the lightest and darkest elements on a printed or displayed image. A photo with a "high" dynamic range means that the brightest and darkest parts of the image are very strong. See HDR.