Wednesday, July 18, 2012


This really bothers me!  How does this work?  How is it that our eyes, like photography, "develop" a positive image from a negative?


Anonymous said...

Okay, here is the answer I found for your question - Sandy:

Well, it has to do with what is called color opponency in the retina. What you are seeing is called a complementary color after image. In that picture, you are effectively looking at a color negative. It is like staring at a red square for a while and seeing a green square after image on a white wall. In a nutshell, the cone cells (color receptors) in the retina are set up to maximize contrast, which cells around them help do by emphasizing opposite colors. When you stare for a long time at one thing, the cone cells of different color sensitivity get “tired” of that color and leave the complementary, or opposite color in predominance. Since you are already looking at a negative, what is left is the positive image.

Yeah, I know. That isn’t very helpful, but it is explainable! I just need a hour or two of your time and a blackboard!

have camera, will travel said...

Makes sense! I'm just noticing this comment two years later! lol Thanks for the explanation and for visiting my blog.