
Now that you've found the perfect photo on the Internet, you're ready to see if you can buy it for your project. So how do you buy a photo you found on the Internet?
Google Images?
Searching Google images for a specific photo can be a mind-boggling experience. There are just so many to choose from. But once you've found that perfect image, go to the site where it's posted and contact the site's administrators and ask for the contact information of the person who owns the rights image.
This is a lot easier done now that Google started to add IPTC metadata from the image to its results. When available, the result will not only show a preview of the image and the website it's pulled from but also details on the author's name and copyright owner, so you can jump onto contacting them to discuss permission to use the image.
Image Recognition – The Future is already here

You may also consider using a image recognition online-tool like TinEye. TinEye is a reverse image search engine. You can submit an image to TinEye to find out where it came from, how it is being used, if modified versions of the image exist, or to find higher resolution versions.

If you have found a image on Google Images, just put the URL to the image into the TinEye Website you may find the stock agencie where it came from and where you can buy it.
Contact the Photographer
If the photo has a caption and is attributed –or if this information was provided on Google Images search results– it can be tempting just to contact the photographer to secure permission to the photo. However, more often than not, the photographer doesn't own the rights to the image at all, their employer (or copyright owner) does. It can be a huge hassle to hunt down the right decision-maker but don't cut corners. Make sure you do the work to secure the appropriate rights before you use the photo.
If the process of hunting down the individual owners of the images seems daunting, you can visit a stock photo agency and see if they offer a similar image. It's likely you will be able to find something similar and the process of dealing with a stock photo agency is much simpler than with individuals and will likely cost much less.