If you want to create a direct link to a public image on Google Drive you may use Permanent link generator that I crated for my personal use.
Note (28/09/2016): Google does not support this anymore!
Where is it?
The tool is available as a simple HTML page here: Permalink
The source code: Permalink Source Code
How to use it?
- Upload an image to the Google Drive, locate it, right click and select Share option
- Click Advanced and make sure the image can be viewed by anyone on the web
- Copy the Link to share and paste in the Permalink tool
- Click Generate Permalink to get links to the image
- Share the link or use it on your website!
The way the links are generated is described here: http://googlesystem.blogspot.com/2013/02/permalinks-for-google-drive-images.html