Arnoud Quanjer Wildlife Photography

Dynamic range is the measure of an imaging system's brightest subject to darkest subject. It answers the question, "How much tonality can I capture in a single exposure?" and the answer is far from simple. Digital photography attempts to hang on to a useful dynamic range right up to the point of whitest white. One can see this in an editing program such as Photoshop as a brightness of 100% or and RGB value of 255, 255, 255.

Everything under that point is represented by a smaller percentage or numerical point in RGB space.

In ergonomic terms this means more to us humans when it is represented in percent, so this article will discuss it that way.

At 100% a pure white result prevents there being any brighter detail. The ceiling has been banged into. Your print paper will accumulate no ink; your computer monitor won't push more electrons or your flat screen LCD elements will be completely illuminated. Presumably, at 0% the image will report nothing but totally black pixels, allowing no more detail to be derived from the exposure. Prints at this point will have piled on so much ink that nothing darker could be added to the paper from the printer.

In the photographic world of film, digital images are like transparencies --slide film-- in that once you've overexposed, that image is going to resist being effectively diminished in brightness during a rescue operation. Slightly underexposed slides can be printed a bit lighter by simply allowing more light through the enlarger. The contrast of the reversal paper is high enough to tolerate a reasonable amount of exposure increase. Scanning slides into the digital realm also lets the photographer lift and shape the tonalities of the image right up to the point at which highlights are bleached to white.