Because of insensitivity at the blue end it's in the blue channel that you will almost certainly find the most noise in a digital photograph or scan. In some cases it can be helpful to open the blue channel in software such as Adobe Photoshop and apply a moderate amount of softening. Expect more noise to appear in situations with low light levels where the noise to signal ratio will be at its highest. Perhaps surprisingly, a lack of noise can also be a problem. One reason that computer generated images such as those from 3D rendering programs, look so artificial is that they lack noise.
Gradations are perfect in tone and color and edges are unnaturally abrupt.
Keep this in mind if you are photo retouching and applying gradations or tone fills. It pays to also add a little noise. All rights reserved.