Google Blogoscoped has a groovy blog post about restricting Google Image searches to find items that are a particular color. Not a particular color type — grayscale or full color — but a specific color. He’s put up a form on his site to let you do the searching, but if you don’t want to use that you’ll have to do some URL hacking.
The URL tweak to do color searching is
Replacing green with whatever color you want, of course. Not every color will work — you can’t put vermillion in there — but the basic colors should get you some results.
Bear in mind, though, that Google Images will find the color. It will not necessarily find color in the object. If you do a search for a green giraffe you will find very few green giraffes. Mostly you will find normal-colored giraffes on green backgrounds.
You can search for multiple colors by separating them with a comma. Here’s a search for brown and green giraffe pictures. I noticed that searching for more than two colors pretty much restricted my search results into oblivion, though you may have better luck with more general keywords.
Interestingly I could not find a way to exclude colors from the search or do an OR for colors. While I was poking around Google Images’ advanced search page I did note that you can now search for items of a very specific size, not just a general small, medium, large, etc. So, 800×600 images of cows with green in the pictures? No problem!
On the other hand, you may want to just get a general idea of what pictures go with what colors. Do a search for a, which at this writing will bring you about 943 million results, and just append your color searches on to it. Even here, though, I find that doing searches for more than two colors at a time really restricts my search results.