What's in a name?

The book I chose for my free read was "The Color Purple" by Alice Walker. Reading the title, I really didn't know what to expect what this story will be about. I knew this book was about slavery and all its unjust behaviors that came with it, but I didn't know what the color purple exactly meant for the book. I once studies colors in psychology and the color purple is associated with pride, independence, and power. Understanding what the story plot is, I assumed that the story was going to focus on an "owner", some higher power, being a prideful, ignorant jerk and a slave, with ultimately no power, who wanted to claim their independence and power through the discriminatory abuse. The title being "The Color Purple" drew me in because it intrigued me to know what represents that color purple exactly. Does the color signify the slave is some way? Was there another meaning to the color purple during the time of slavery, does it have a racist negative connotation? I really was dumb founded on to what the title has to do with the overall plot of the book. There's so many things that could be behind the color purple. I thought to myself, maybe the slave escapes when the sun is setting and the sky is purple and it means independence, and the slave running away would be gaining their independence, so thats how purple ties in. I was trying to connect the dots, but as much as I tried I couldn't. It made me frustrated but made me eager to read this book, as I know it's one of Alice Walkers most greatest works. The title just doesn't reveal much about what this book can be about and had left me hanging for answers already.
http://movies2.nytimes.com/books/98/10/04/specials/walker-color.html