After much research, it appears that at minimum, one should indicate the photographer, the Creative Commons license and link to page where found and/or photographer's profile page on Flickr. So the minimum attribution for the photo below from Flickr would be Photo used under Creative Commons license from cronegeek. (Note Flickr wants one to provide a link back to Flickr. And many other web sites also want you to provide a link back to page where photo appears.)
Alternatively, when working with Flickr photos, one can use the app at Imagecodr.org to produce a photo with the attribution at the bottom as seen below. [For this photo I displayed the small size at Flickr and then input the URL for the small size page into Imagecodr.org.]
On the Get Code page at Imagecodr.org there is a button that you can drag to the toolbar on your Web browser for instant access to Imagecodr..
To search for images with a Creative Commons license one can go to
- http://search.creativecommons.org/ where you can conduct searches from Google Images, Flickr, and other places and have your results limited to only images with Creative Commons license. You can also specify whether you want images that can be modified (legally) and/or used commercially (legally).
- http://compfight.com which also searches just Flickr, but tends to give more images than either of the sites above.