A single convex  lens, such as a refractive sphere, will not only invert an image it will also reverse it left to right. 
The process of vision, once it is inside the head becomes an extremely complex process that is generally the same in overall result but unique to each individual. This is especially true in terms of colour perception. (Did some looking into human factors research early on in my career.)

Pass no temptation lightly by, for one never knows when it may pass again!