Just for some design ideas to take into account when writing/finding your solution:
There are two ways of doing this, one with multiple chopped up images that preload when the user scrolls near them, and the other which is simpler and loads one big image.
If your image(s) are very big, you should opt for a solution that preloads segments as this will be a lot more user friendly if you can do it seamlessly.
The big image will slow down some computers/mobile devices significantly!
