The vision system of living things is awesomely impressive. It has taken around a billion years to evolve from light sensitive spots on the skin to the advanced vision system we have today. It uses incredibly sophisticated sensors, the eyes, linked to a huge brain - about a third of which is used for visual processing - to process the data from the eyes; and it combines that and memory to assemble a live, detailed 3 dimensional image. The eye-brain-memory combination also has a subconscious function that detects and alerts movement of potential predator threats.
The result is a full colour, real time*, moving, three dimensional, detailed vision-scape.
Those visual tests you have to pass when registering with certain internet sites - 'click on the photographs containing traffic lights, or zebra crossings, or type in what the wonky letters are';to prove you are not a robot; show how basic computer vision systems are at the moment.
*A few hundred milliseconds delayed owing to all the sophisticated processing.