For some people there is cross-talk between the senses. A musical chord may look purple, or a colour may have a taste. This is synaesthesia. It may enrich experience with its own poetry. Although the code for the messages from the senses is simple, the brain's task of de-coding to give perceptions of objects is so complicated we only partly understand it.
Optical images are extremely different and much simpler from the objects they represent.
The images in our eyes are but shadows of the solid, threatening and rewarding objects that we see around us every moment of the day. This needs knowledge of tables, knives, and people - of everything we see and recognise, in pictures or reality. This is not at all simple. Much is created in the brain. Colours are created in the brain and psychologically projected into the world of objects.