In a module I'm creating, I want to use a custom image as a button. I do not know where to save the image, and how to reference it from the view's xml...

The image looks like this, and will be used to fetch a weight from a scale into a field.

http://i58.tinypic.com/2rw2ueh.png

I've read about solutions with saving the image in /addons/web/static/src/....... path, but this kind of breaks the portability of the module. I want to save the image in a subfolder of my addon's folder, so it just comes preinstalled with the module.

What folder should I use, and how can I access the file from a view afterwards?