It might be a little more informative to differentiate between "noise" in a digital image on one side and grain in film and pixels in digital on the other side.
The grain in a film image is the irreducible element in the formation of the image just as the pixel is such an element in the digital image.
"Noise" on the other hand is the appearance of image elements in the image that do not correspond to light values in the original scene.
It is an artifact of the amplification of the signal coming from the sensor chip and, as such, is an error in the image formation.
As I recall, subject to correction, the corresponding image elements in a film image to 'noise' in digital is referred to as "fog",
This consists of film grains that convert to silver in the absence of a corresponding light value in the original scene, i.e., no exposure.
So, Film Digital
Grain <=> Pixel
Fog <=> Noise
FWIW, that's how I remember things.
Cheers,
James
At 10:47 AM 9/4/2006 -0400, you wrote:
I guess I'm a hopeless carryover from film days but I'd rather use the word 'grain' instead of 'noise'. Actually this digital 'noise' makes no sound. Bob M leica@xxxxxxx
