Well, the sensitivities of their eyes have been researched for quite some time, also the neuronal processing they do in their optical systems in their brains (there are various theories though), but what they actually "see", we cannot imagine.
What I have done is map their sensitivities and subsequently my images (which were done using matching filters) into out human color space, hence why I call it "simulated" bee/butterfly vision as no-one can really know.