The physical action registered by the eyes is called light. But vision is much more than merely having an eye for the colours of the rainbow. At first the pictures will seem black and white.
More light shows that they're actually in color.
Your color vision is less sensitive than black and white. This house has slanting walls and inclining floors. The house seems quite normal, however, if you observe it from a particular angle. Or test for distance perception or structural defects. The computer will start by showing you 8 colors in random order.