What is photographic noise?

Question: What is photographic noise!?
Best Answer - Chosen by Asker:

Noise is a random variation of image density, visible as grain in film and pixel level variations in digital images!. It is a key image quality factor; nearly as important as sharpnessWww@QuestionHome@Com

There is photographic grain that depends upon the brand and ISO of the film

There is A/D processing noise that occurs when high ISO image data is set through the camera's image processing algorithms !.!.!. the noise is generated by the amplification of weak image signals being sent from the cameras sensor similar to the noise induced when you try to use a low powered MP3 player to play loud music!. It is called clipping when audio is involved!.!.Www@QuestionHome@Com

In Physics (noise) means: A disturbance, especially a random and persisting disturbance, that obscures the clarity of a signal!.

In art (noise) means relatively the same thing!. Noise is looks like dissolved dots all over a piece of artwork!. These dots make the picture look pixilated and have low clarity!. Noise in photography and other digital arts can be both a nuisance and a fun artistic form, depending on where and how you use it!. I hope this helps!.Www@QuestionHome@Com

Check out this site:
http://www!.imatest!.com/docs/noise!.htmlWww@QuestionHome@Com