Just because you found that photo on the Internet doesn’t mean you can use it for free. Check out this link where John Mueller summarizes the total cost to recreate a sunset image.

http://www.petapixel.com/2012/01/10/this-photograph-is-not-free/

So, next time you’re looking online for an image to use, you might want to consider asking for permission, or looking at a stock photography site. Might be worth the extra effort.