Does dark gray on a red appear green to you when on a product in equal amounts? Kinda like on the Nike Free shoe shown below? To me it does look green at first glance giving me an impression of red and green Christmas colors… until I look closer. I like the holiday season and all but not all year round. Cheers, Scrooge 
No, not at all to me. But I am curious as to why it may appear green to you. I just did a little research but could not find an answer as to why red and gray might appear green.
It does for some reason and wanted to see what other designers thought… maybe I’m a bit color blind or all the green and red this christmas is jarring my color receptors. I looked it up, too… thanks.
Now that you mention colorblindness, this may be a clue… Seeing, Hearing, and Smelling the World | HHMI
Interesting. It doesn’t look green to me either. Sorry.
When gray is placed next to a color, it can take on a tint of that color’s complimentary color if you stare at it long enough. Complimentary color for red is green (opposite in the color wheel). I don’t know if it has anything to with color blindness, but apparently some people see it easier than others. Although, among most color blind the red and green will both appear as brown. That’s why one should never rely on color alone to relay function, which unfortunately is very common for - that’s right - red and green.
Also see: chromatic gray.
I see red first, grey second, and red still stays dominant color to me.
engio, this may be it… where did you learn this from?
robertcj, great links. I can discern between red and green so I don’t think I’m colorblind. simultaneous contrast makes sense.
When you have a red light source (any red light bulb will do), and shine it on an object in an unlit room, the shadow projected on the wall will be green. Same with orange light, blue shadow, etc, etc. Could be your brain tricking your eye into this same idea?
I’m thinking this could be the case as the bold red color takes the forefront to the gray here, and the gray almost looks like a shadow in comparison.
Also- for me- (and maybe its because you asked this specific question and I can’t help but force the reaction)- its the black Nike swoosh, not the gray area, that appears to have a very light tint of green while I stare and zone on in the middle of a red section.
I remembered stumbling upon it in the Design Bites ( http://www.design-bites.com/booklets/human-factors-and-aesthetics/prod_5.html ). It’s a great collection of rules of thumb and general stuff boiled down to the essentials.
You could be looking at the red too long before looking at the grey. Like that old trick where if you stare at a red card for 30 seconds then look at a white wall, you’ll see a green (opposite of red) shadow of the object you were staring at. Something to do with retina burn-in… or something gory like that.
This may be of interest.
R