This is an Adobe Photoshop Video tutorial that explains Tonal Range, and the difference between Levels and Curves. While each of these topics is technically different, they each work with the same basic principals, so I thought it would be helpful to understand them, if I covered them all at the same time. Before you seriously get started working with RAW Files, you need to understand Tonal Range, and how the different Sliders affect different aspects of the image.