Has Anyone Else Ever Seen Very Blue Shadows Outdoors?

[John Hollenberg]

I couldn't find a good place to post this question so selected color management.  Has anyone else ever seen blue shadows outdoors?  I am not talking about the image from a camera, but what I saw with my own two eyes.  Only happened to me one time.  I had hiked about 10 miles with a heavy backpack at high altitude (10,000 feet plus) in the Sierra.  I was completely exhausted.  Suddenly I noticed that the shadows were very blue to my eyes.  I'm not talking about a slight blue tint, the shadows from trees and rocks on the hillside turned a very obvious blue.  It was the weirdest thing I had seen in a long time.  No one else on the trip saw anything unusual.  It lasted for 20-30 minutes then resolved.  My hypothesis was that while our brains normally adjust the shadows to be basically neutral (unlike film or digital camera if white balance set to daylight) there was a failure of that compensatory mechanism due to extreme fatigue.  My optometrist didn't have an explanation for the phenomenon.

[luxborealis]

Yes! Especially in winter. The shadows on snow can be especially blue in real life.

At altitude, I’m sure blue shadows are more likely due to the cleaner, thinner air and the higher amount of UV, though, from what I understand, our eyes are not good at perceiving that part of the spectrum.

[Peter McLennan]

I use this situation all the time in my film making classes.  "On a sunny day in winter, why are shadows on the snow blue?"  I pose this question some time after my "key light, fill light, back light" spiel.

Usually, it takes a few minutes of discussion for them to come up with the answer.

[John Hollenberg]

The phenomenon I am referring to was of a different order of magnitude and was a transient experience which I have never had before or since.  The shadows weren't just a different color of light, they were a more intense and brighter blue such that it was impossible to ignore them.   There was nothing unusual about the light in the Sierra that day, it was my perception that was greatly altered for a brief time..

[Peter McLennan]

What was the weather like?  Cloud cover?

[John Hollenberg]

What was the weather like?  Cloud cover?

No, the sun was out.  It was around 5:00 PM which in early August in the Sierra is several hours before sunset.  Over my life I have spent a total of 18 months backpacking in the Sierra in all kinds of conditions, never saw anything like it.  When I asked my companions if they saw how strikingly blue the shadows looked all of them said they looked "normal".  That is why I think it was a unique perceptual experience.

[degrub]

Perhaps low blood oxygen saturation, low blood sugar, dehydration,  or other metabolic issue could create a perception change ?
20-30 minutes is about right for the body to start to recover, particularly if food or water are ingested.
i've had a few times with "altered perception" when at the point of exhaustion backpacking. Don't know the real cause as it resolved itself with snacks, water, and rest.

[Jack Hogan]

I couldn't find a good place to post this question so selected color management.  Has anyone else ever seen blue shadows outdoors?  I am not talking about the image from a camera, but what I saw with my own two eyes.  Only happened to me one time.  I had hiked about 10 miles with a heavy backpack at high altitude (10,000 feet plus) in the Sierra.  I was completely exhausted.  Suddenly I noticed that the shadows were very blue to my eyes.  I'm not talking about a slight blue tint, the shadows from trees and rocks on the hillside turned a very obvious blue.  It was the weirdest thing I had seen in a long time.  No one else on the trip saw anything unusual.  It lasted for 20-30 minutes then resolved.  My hypothesis was that while our brains normally adjust the shadows to be basically neutral (unlike film or digital camera if white balance set to daylight) there was a failure of that compensatory mechanism due to extreme fatigue.  My optometrist didn't have an explanation for the phenomenon.

Other than some physiological effect (did you also see a few pulsating stars?  = blood pressure dropping when stopping after exertion) shadows on a sunny, clear day at high altitude do not get direct sunlight but are instead illuminated by the sky alone.  Such sky on Planet Earth is Blue so since you were most likely adapted to around D50 it looked blue to you (And There's Nothing I Can Do...).

Jack

[Doug Gray]

Perhaps low blood oxygen saturation, low blood sugar, dehydration,  or other metabolic issue could create a perception change ?
20-30 minutes is about right for the body to start to recover, particularly if food or water are ingested.
i've had a few times with "altered perception" when at the point of exhaustion backpacking. Don't know the real cause as it resolved itself with snacks, water, and rest.

That would be my guess too. O2 levels at >10,000 ft are lower and hypoxia and body chemistry changes, particularly after heavy exertion, seems the likely explanation. People have differing reactions but changes in vision are common. That it resolved after half an hour is another indication.

[John Hollenberg]

Perhaps low blood oxygen saturation, low blood sugar, dehydration,  or other metabolic issue could create a perception change ?  20-30 minutes is about right for the body to start to recover, particularly if food or water are ingested.  i've had a few times with "altered perception" when at the point of exhaustion backpacking. Don't know the real cause as it resolved itself with snacks, water, and rest.

Probably the best guess.  I thought it might be a manifestation of an ocular migraine (no headache after the aura), but while I have had those a few times during heavy prolonged exercise they always present with blurry vision especially in the center.  The optometrist did not think that likely.  I had one other time when I "bonked" after 7 hours of largely cross country hiking.  We were hiking up Mather Pass and I found myself going slower and slower until I completely ran out of energy.  No perceptual changes then, recovered with some food, water and a brief rest.

Reminds me of the great variety in perception:  "I see colours you cannot perceive or imagine."

http://www.bbc.com/future/story/20160316-i-can-see-colours-you-cannot-perceive-or-imagine

(Not that I have that kind of color discrimination, although on the test where you arrange similar shades I only missed one place where two color were switched improperly.)

[Doug Gray]

Reminds me of the great variety in perception:  "I see colours you cannot perceive or imagine."

http://www.bbc.com/future/story/20160316-i-can-see-colours-you-cannot-perceive-or-imagine

For an interesting academic paper on Antico and one other participant with less color training see:
http://static.concettaantico.com/BochkoJameson2018_published_compressed.pdf

Apparently tetrachromats, among women, should be much more common. So far, testing shows almost all genetic tetrachromats are effective trichromats.

[Telecaster]

Color perception is context dependent. Could be the other colors/tones in the scene, at that particular moment, resulted in seeing intensified blue in the shadows.

-Dave-

[John Hollenberg]

Color perception is context dependent. Could be the other colors/tones in the scene, at that particular moment, resulted in seeing intensified blue in the shadows.

Yes, that is possible.  However, at high altitudes above tree line in the Sierra the colors/tones in the scene don't change much from one place to another.  Of course, they do change with the light, particularly in the golden hour.

[Ernst Dinkla]

No cataract surgery endured lately?
Face one in some months.

Ernst, op de lei getypt.

[John Hollenberg]

No cataract surgery endured lately?
Face one in some months.

No, I have a tiny cataract on one side that is not affecting vision at all (fingers crossed).  I do have a few floaters.