A few weeks ago, I wrote how you could filter your Google Image search results by color. All you had to do was add a small string of code (&imgcolor=colorname) to the end of the results' URL and redo the search.
Now Google has made it even easier to filter images by color. After you search for your image, a drop down box will appear below your search term, next to the All Content drop down box. Click on a color, and your results will automatically be filtered by that color.