Chapter 3 - Digital noise: What it is and how to deal with it

Abstract

Noise in digital photographs is the visual equivalent of static you hear in radio signals, and most digital cameras add some level of noise to images. In traditional photography, the nearest equivalent is film grain. Like film, digital noise is noticeable in images shot at high ISO settings, and more visible in areas of uniform color, such as skies and shadows. Digital sensor noise may also be increased when long digital exposures are made under lowlight conditions, such as night photography, and noise is always more obvious in areas of underexposure.