Like everyone has said thus far, snakes have very limted vision, which like most reptiles, is based on movement (i.e. if it's not moving, its not alive). Now, the vipers and pit-vipers, as well as many boids (like your python), have heat-seeking pits along their lips, and studies indicate that these snakes see in the infrared. This still doesn't imply that they see a sharp image, though. If your python were looking at you, it would probably see a huge reddish orb (your head) and two long red shapes (your arms). Even if you stayed still, it would recognize that you were a living thing. But your scent would tell it that you're not prey and your behavior would suggest to it that you're not a threat. Over time, I do think that many pythons learn to distinguish their owners' scent from other people. I often find that if my python is out being handled by a bunch of people, and I'm one of them, then he tries to get back to me no matter whose holding him. Am I readng too much into that? Maybe...but who knows?
Now some snakes are a little more visually-oriented than most, like cobras, coachwhips, indigos, etc which all seem to rely more on sight for hunting. But how superior their vision is compared to other snakes is unclear.
