The Zone System is a technique that was formulated by Ansel Adams and Fred Archer. It is an approach to a standardized way of working that guarantees a correct exposure in every situation, even in the trickiest lighting conditions such as back lighting, extreme difference between light and shadow areas of a scene. I've used the Zone system to edit my own photos so I can get the perfect balance in tones. I used Photoshop to change contrast, hue and saturation to get a wider range of shades to finish with a perfect image with many tones.