I've been dressed in solid orange and one time had a deer walk up to within 5 yards trying to figure out what I was. I didn't have a doe permit that time, I didn't move and she ended up calmly walking away.
That's the trick. Your camo dosen't even need to blend in that well if youkeep your butt still, and don't stink too bad.
Anyway, Kevin put up a nice chart on the black and white rods, and I found another one before I saw his. This one shows the difference in how color is detected due to different numbers of different types of color receptors. It's all about wavelength and having the right tool to see it.
Here is the technical explanation that accompanied the chart above.
These graphs illustrate the difference between the Daylight (color) vision of the Human and the Whitetail deer. Each trace reveals the profile of sensitivity of a single class of receptor. Notice that the deer has only blue peaking and green peaking receptors while the human has a third receptor that is normally referred to as “red” because it gives us the ability to see red light. This third cone makes us far more sensitive to the longer wavelengths (such as blaze orange at 605 nanometers). Notice also that the sensitivities of our blue receptor and the short side of our green receptor are less than that of the deer. This is the result of our Ultraviolet (UV) Filter that is absent in the deer. It makes us unable to see UV and far less sensitive to all wavelengths below 500 nanometers. The color bars illustrate the full range of color and brightness that each would see if deer and human both observed the spectrum in equal brightness.
This is the text for Kevin's chart.
Scotopic or rod vision is the black/white/gray capability in low light conditions at the peak hunting hours when these animals are most active. While deer are clearly superior in low light at all wavelengths, the advantage is greatest at wavelengths where the deer’s sensitivity continues after human vision has ceased (Blocked by the UV Filter). This graph illustrates the extended capability of game animals and birds to see beyond our visible range. Note that at 400 nanometers (where human vision is fully blocked by our UV filter) the game animals have greater sensitivity than humans have for Blaze Orange. For ease of illustration, a logarithmic scale is used to compress the huge advantage in rod sensitivity of the deer.
According to this, not only can they see blue, but they see it better than we can and anything that reflects UV will glow brightlyto them,like Blaze orange does to us. So, don't use UV brighteners in the laundry, and check out your new camo in person before you buy. Don't get anything that glows under blacklight.