because you can now overlay onto other RGB rasterized images
The SVG is just the spectral map. We're using its native possibilites to pull off some other crazy wild hare of an idea to do things that other image compositing programs do, but in a browser. I'm way way outside a box here, but that's where I prefer to play. This is one of those things where I'm taking an idea that someone developed with a specific idea, but I'm jerking the wheel hard left to suggest something zanny just because it might be interesting and cool. Following directions and creator's intent is boring ;-)