Aug 222012
Most of the images on this site are from U.S. Government free image archives. Some have been Photoshopped more or less extensively. There are some amazing free images available from the U.S. Government, which can’t copyright them, so they are free to everyone to use. Your tax dollars at work, and a good thing, too.
Here’s a few of the best sources:
US Geological Survey EROS project
National Human Genome Research Institute