This Photoshop tutorial is designed to instruct on the use of Photoshop's 'Noise Filter' to add back the noise that is inherent in digital and film photography, after retouching. This technique is also useful when you are cloning in a part of another photo that has a higher resolution.
Digital Noise Levels in Photography
Noise is inherent in all photography - film and digital, and when a photograph is shot at a higher ISO setting, or is shot in a low-light situation, it can increase the noise levels dramatically. Much of this is a function of your digital camera's sensor capabilities, and is therefor unavoidable.
When you are retouching a digital photo, any new element that you add into it must be fully integrated to look realistic. Part of this process involves matching the exact noise characteristics found in your photo when highly magnified. To match your existing photo, you will use a variety of filters to achieve a close match in noise level and quality.
