You don't need any special technology to do that which you want.
This is a path "relative" to indicate that the image is in the same directory as the web document that it is loading, for example
index.html. This way, you would have this structure
- Directorio raiz web
On the contrary:
<img src="http://www.w3schools.com/images/w3schools_green.jpg" alt="W3Schools.com">
It is a path to "absolute", represents all of the complete address where is hosted the resource. Includes schema
http://, host or server,
www.w3schools.com and the path or route
/images/w3schools_green.jpg in this way, it is not necessary that the web document and the resource are in the same directory. Not even in the same server.
To do this, you need a web server (apache, nginx, etc) although any of the options that you have commented, such as picassa, you can use. Just keep in mind that when you indicate the attribute
src of the image, you'll need to put these three elements that I mentioned to you,
esquema o schema,
servidor o host and
ruta o path.
This is equally applicable to the attribute"
href of the links, which can be relative or absolute.