Okay I'm building a database of keycaps to be used as a reference to obtain this kind of images thanks to a software I'm writing (please consider it's in a very early development phase)
It's a very long process, I have just 140 keycaps so far to test the algorithm but the end result is very nice already, so I'll keep grabbing keycaps around to achieve better results. I believe the sweet spot is around 400-500 keycaps. I especially miss the light not-saturated colors (light blues, light greens, light yellows, skin tones, ...).
If you find pictures of keycaps taken from above please post them (the higher the resolution, the better). If there's interest in such a tool I'll put it online and release under open source license so you can keycapize your own pictures.