Essentially, using the gridPositions.json to populate a Voronoi Grid (toggle display of the <canvas> in your browser). Then your cursor position is used against the grid to find which shape encloses it which maps back to the source JPEG which is then displayed.
You can tell he/she "cheated" a bit for some the parts of the canvas that didn't get many seeds. For example, if you move your mouse within one of the large cells in the bottom left, the image just moves to keep up with the pointer. :P
You don't need a different picture for every single pixel: if the picture is large enough, you can easily crop it and use it to cover few thousands pixels.
Are the developers willing to share some insight into how this works? The picture selection is right on and there seems to be a good number of pictures at that.
Seems like it's Win/Chrome.
One way to make it work is to right click where you want it inside the square it and then left click anywhere outside the square.
There are likely some good opportunities for this code however speed of response may be a problem? Runs a little slow on my PC.
There are around 900 of them! I'd have used Amazon's Mechanical Turk...
Very cool effect, I also wasted way to much time playing with it :)
However, if that's all they're doing, it seems odd that it takes so long to load... Maybe some of that's just a built-in delay to keep from constantly cycling images from someone who's bumping the mouse.
1: It will be one click less, for those who use noscript.
2: It will allow your site to survive the case that jquery.com changes anything, or goes down.
Besides that its a nice toy.
The actual positions are saved in a json file.