What do bees see? That question does not have an easy answer. Vision is a sensation produced by the brain. We can never know exactly what a bee sees. The best we can do is to determine what a bee is capable of seeing.
The compound eye of the bee is composed of many hexagonal units called ommatidia. Light hitting the compound eye of an insect is converted by the ommatidia to nerve signals that are sent to the brain.
It is helpful to think of ommatidia like pixels on a computer screen. Each ommatidia sends information to the brain about the amount of light for its own location (pixel). Information about the shape of objects would require the bee to combine the information from all the ommatidia into a single picture, the way the pictures on your computer screen are produced by thousands of pixels.
Scientist, Andy Geiger, has a website called beye that displays visually what a bee is capable of seeing. Geiger uses computer simulations of an image of an Escher painting of an ant as an illustration. The Escher illustration is projected onto a virtual bee eye. The light/dark reaching each ommatidia is calculated and the image corrected for differences in the size of the ommatidia and the angle relative to the image.
The computer shows us that the information sent to the brain of the bee would “look” very different from the way the same image would be processed by the human eye. The bee image is highly pixelated, warped and not very detailed. The ommatidia of the bee compound eye are far less numerous than the photoreceptors of the human retina. Our brain receives far more detail that that of the bee.
Bad Science Fiction movies often portray insect vision as an array of complete pictures as if each ommatidia functioned as a miniature camera (as discussed in a previous post). The Science Fiction version is strictly artistic license to communicate to the audience that we are seeing the insect POV. The artistic license is far from what any insect is capable of seeing.