Color and color value are critical to the success of our quilts. Any one of these books will help you gain color confidence and learn to express yourself in fabrics when you stitch your quilts. You might also want to read my articles: Color Value for Quilters and Color Wheel Made Simple.
Joen Wolfrom uses the Ives color wheel instead of the wheel we normally see, and she approaches color from a different perspective. She focuses on colors in nature and shows you how to play with and mix colors in ways you might not have considered.
Gai Perry's book is a hands-on approach to color. She tells you the specifics of what working with color is all about -- but the exercises she provides to walk you through color selection are the real key to your success.
First, a disclaimer. My name is on this book. I don't receive royalties from it, and honestly, I don't remember why my name is on it. It was freelance work, but Susan McKelvey is the color person and she does a great job explaining how to use color in your quilts.
Katie Pasquini Masopust offers technical details and plenty of hands-on exercises to get you comfortable with selecting colors for your quilts.
Ms. Wolfrom approaches color in an easy-to-understand way. Read my book review to learn more.