Flickr is an image sharing social network with billions of photos. A lot of these photos can be used for free and many are of high quality. But how do you find out which Flickr photos are free and how do you sort out the best one? Multicolor Search Lab is a free tool with easy to use visual interface that lets you browse the best free photos on Flickr and find the one you want.

Multicolor Search Lab is developed by the Canadian visual search software developer Idée Inc. Their tools are sold to companies like Associated Press, Agence France–Press and Digg, but you can use them for free on Flickr’s database. How does it work?

Multicolor Search Lab searches for images containing particular colors. Pick the colors you want from a color palette containing 120 colors (click the trash can icon on the colors you want to discard). You can pick up to ten colors, which should be adequate for most users.

This tool should be great for artists, web designers, and other creative occupations.

Multicolor Search Lab searches 10 million Flickr photos. The photos are selected for their “interestingness“, a Flickr quality indicator that combines (among other things) where the clickthroughs are coming from, who comments on it and when, and who marks it as a favorite. It works quite well and the photos displayed are generally of high quality.

So are all these photos really your to use, free of charge? Yes. Here’s why and how: All the photos displayed in Multicolor Search Lab are tagged with Creative Commons (CC) licenses. When you click through to a photo’s page on Flickr, you can see what kind of CC license applies (in the right hand column under the heading Additional information).

There are six kinds of Creative Commons licenses. The most basic is called an attribution license and photos tagged with this license can be used free of charge as long as you mention and link back to the photographer. The other categories apply certain restrictions like: You may not make changes, you cannot profit from the use etc. Explore the six Creative Commons licenses here.

You might also want to take a look at these articles:
3 great ways to find free images
Free online image search tutorial