Free Chapter for my new book – Understanding Adobe Photoshop CS5: Color Correction and Enhancement http://www.peachpit.com/articles/article.aspx?p=1613316
"Learning how to spot problems in your images and then choosing the right correction technique is an essential part of mastering Photoshop. Richard Harrington describes the most important tools and shows you how to use them to make the best color correction and enhancement choices.
The primary purpose of Photoshop is to act as a digital darkroom where images can be corrected, enhanced, and refined. How do you know an image needs touch-up? You can pretty much assume every image can look a little (or even a lot) better than how the camera captured it. Whether it’s adjusting the exposure, increasing contrast, or boosting saturation, Photoshop is the place to improve an image."
Check out the free lesson here.