Here is a quick fun thing you can do in Yosemite to make your desktop easier to read. You can change the background color of you title bar and dock to a dark color. The effect will vary depending on your desktop color. Mine happens to be a medium gray.
To do this select Apple Menu > System Preferences > General. There is a new little box under Appearance. Check the box next to “Use dark menu bar and Dock” You can always uncheck it if you want to go back to the original option.