Image noise is random (not present in the object imaged) variation of brightness or color information in images, and is usually an aspect of electronic noise. It can be produced by the sensor and circuitry of a scanner or digital camera. Image noise can also originate in film grain and in the unavoidable shot noise of an ideal photon detector. Image noise is an undesirable by-product of image capture that adds spurious and extraneous information.
The original meaning of "noise" was and remains "unwanted signal"; unwanted electrical fluctuations in signals received by AM radios caused audible acoustic noise ("static"). By analogy unwanted electrical fluctuations themselves came to be known as "noise". Image noise is, of course, inaudible.
The magnitude of image noise can range from almost imperceptible specks on a digital photograph taken in good light, to optical and radioastronomical images that are almost entirely noise, from which a small amount of information can be derived by sophisticated processing (a noise level that would be totally unacceptable in a photograph since it would be impossible to determine even what the subject was).
Read more about Image Noise: In Digital Cameras, Image Noise Reduction, Video Noise, Useful Noise, Low- and High-ISO Noise Examples
Famous quotes containing the words image and/or noise:
“Bring us the mirror, you ignorant thing, and be sure not to sully the image by the transmission of your reflection!”
—Molière [Jean Baptiste Poquelin] (1622–1673)
“I’ve almost gained my heav’nly home; My spirit loudly sings;
The holy ones behold they come, I hear the noise of wings.
O come, angel band, Come and around me stand.
O bear me away on your snowy wings, To my immortal home.”
—T. Haskell, minister and hymn-writer. Published in Christian Harmony. “Angel Band,” l. 5-8.