Taking the last sentence first:
That said, IF the original color of the shoe was pink and white, it's interesting that some people see it that way after it was shaded. In fact, it's not just interesting, it's downright weird!
It's downright weird!
But the claim that the shoe is pink and white is not true.
Disregarding philosophical hairsplitting over primary and secondary qualities, I think it's common convention to refer to something's color as what it appears to be under normal (white light) conditions. Like Neil said above, "I can make my hair green and my skin purple on my forum profile with just a couple of clicks, and most people would probably still be able to ascertain that I'm white."
If you're looking at a white sheet of paper through yellow-tinted glasses, what color is the paper? Perhaps it would be best to say that
when wearing such glasses, you perceive it as yellow, whereas under normal conditions (i.e. white light) it is white. It is white paper, filtered through yellow so that it is perceived as yellow.
So technically the pink/white people are technically correct in that the shoe itself as an object existing in the world IS pink and white, the same way Neil is white and not purple, regardless of whatever filters he applies to his picture of himself. What's most interesting and weird is, as you say, that some people SEE the picture as pink and white, when those are NOT the colors on the screen. That would be like looking at said picture of Neil and not being able to tell that it has a purple tint... Or looking through yellow-tinted glasses and SEEing white paper. So in that sense, they're wrong.
I've got a question for habitual blueblocker wearers: does it ever get to the point where you don't realize you're looking through tinted glasses, and see white objects AS white? What comes to mind is the inverted-glasses experiment where the subject wears glasses with mirrors configured to flip the visual field so the world is upside down. After some days, they become habituated to it and can function normally, as if the world is right-side up. But then, after taking off the glasses, the world is "flipped" again, and it takes up to a day to recover the sense of normality.
en.wikipedia.org
And one YouTuber's experiment doing so:
Writing the above made me wonder about adaptive effects of the visual system regarding color perception. Found a couple papers that might be relevant:
The visual system continuously adapts to the environment, allowing it to perform optimally in a changing visual world. One large change occurs every t…
www.sciencedirect.com
Vision is known to adapt to such changes in spectral power. For example, illuminating the surround of a constant test patch with lights of different colors produces large changes in test appearance (e.g.
Chichilnisky and Wandell, 1999,
Rinner and Gegenfurtner, 2000; for a review see
Foster, 2011).
Some of this color adaptation happens immediately, and so is often labeled color contrast, while some of it arises more gradually (
Fairchild and Reniff, 1995,
Rinner and Gegenfurtner, 2000,
Shevell, 2001). In the present study, wearing reddish filters
made a reddish test light appear more neutral in color. The most common explanation for such adaptation is that the rest of the image, which appears more reddish than usual and is relatively dominated by longer wavelength light, causes a reduction in the strength of signals from the long wavelength cones relative to the strength of signals from the other cone types, through some sort of scaling process (for reviews, see
Rieke and Rudd, 2009,
Foster, 2011). Note that such adaptation
partially compensates for the tint produced by the filters, making the visual world more “normal”, as reddish colors become more neutral (
Webster & Leonard, 2008). Greenish filters produce effects in the opposite direction.
If the visual system can learn to adapt to spectacles, then observers who routinely wear colored filters should show larger and more rapid color adaptation than naïve observers wearing those same filters. We tested this possibility, measuring adaptation by recording the effects of a large, uniform surround on the color appearance of a central target. Observers wore and removed colored filters, which changed the spectral power of the surround. Appearance of the target was measured by having participants set it to be “unique yellow”, a shade that appears to contain neither any red nor any green (
Jameson & Hurvich, 1955).
As subjects adapted to the donning or removal of the spectacles, the appearance of the target changed over time, and this adaptation was tracked through repeated measurements of unique yellow. We found
more rapid and larger adaptation to colored filters in habitual wearers than in control participants.
When the environment changes, the visual system adjusts to maintain accurate color perception. Such adaptations happen at different time scales, and l…
www.sciencedirect.com
Highlights
- Many aspects of long-term color adaptation, including its neural bases, remain unexplored.
- The major effect of long-term adaptation to a colored lens or illuminant is to restore the world to its previous appearance
- This adaptation to color grows stronger over days and weeks via mechanisms that are distinct from shorter-term adaptation.
- Learning of familiar color environments appears to strengthen and hasten effects of adaptation in those environments.
When the environment changes,
the visual system adjusts to maintain accurate color perception. Such adaptations happen at different time scales, and long-term effects are of particular interest because they may engage mechanisms of long-lasting neural plasticity.
Long-term adaptation to changes in the color of the environment produce strong and long-lasting changes in color perception, with the general effect of neutralizing the dominant color. Large individual differences and details of the time course are currently unexplained, and the limits of adaptation remain unexplored. Experience with an environment appears to allow observers to adapt more strongly and quickly to it. Long-term color adaptation may serve as a model system for understanding general mechanisms of neural plasticity, including those relevant for therapies for visual disorders.
It looks like adaptation of the type I mention above does happen:
When the mean color coordinates of the environment shift suddenly away from what we are accustomed to,
the color appearance of the world gradually shifts back toward what is was before the change. For example, immediately after putting on sunglasses the world appears tinged with the lenses' color, but the tint fades over time. The first published observation of this phenomenon was in 1694 by de la Hire [
11], a polymath better known for contributions to astronomy and mathematics. In many situations, particularly for smaller changes in illumination or lens color,
much of the compensation happens instantly and has been studied as ‘color constancy’ (for reviews, see Refs. [
12,
13]).
Other perceptual consequences evolve over time. Short-term effects of adaptation to changes in mean color coordinates, from seconds to minutes, have been well characterized [
14,
15].
Though the manipulation required for studying longer-term changes is remarkably simple — observers can just wear colored lenses or sit in a room with filtered lighting over a number of days — surprisingly few multiple day experiments have been conducted.
The first published report consisted of a single observer’s qualitative observation that the world regained its normal appearance over time [
16]. Since that time, fewer than 20 observers have been tested in total, with about one paper appearing every decade [
9,
10,
16,
17,
18,
19,
20••].
What are the effects of multiple days’ adaptation to colored lenses? Formal measurements agree with Kohler’s initial observations that the world viewed through the lenses comes to regain its prior appearance. For example, wearing red glasses or being exposed to a red environment
causes unique yellow settings to shift by greater and greater amounts across days (
Figure 2; [
8,
9,
18]). The shift is in the direction of more reddish color coordinates, indicating that what previously appeared reddish is becoming more neutral over time,
canceling the effects of the lenses or lighting. Effects of multiple-day adaptation are much longer lasting than the effects of short-term adaptation [
8], remaining robust when measured the morning after a day of wearing lenses, before donning them for a subsequent day [
9,
18,
19]. Because of this endurance, observers often are adapted for only part of each day [
9,
18,
19,
20••].
Here's a graph showing the phenomenon:
If I'm reading it correctly, what you're seeing in the right third of the graph is literally a progressive change in the subjective perception of a color under ordinary lighting conditions. After removing the red glasses, the perception of the color yellow actually changes, which is quite amazing!
However, when this paper was published (late 2019), it was unknown if vision ever achieves "full normalcy" while wearing tinted glasses longterm, as it seems to do in the inverted-glasses experiments.
They offer this possible (though partial) explanation for the phenomenon: "Adapting to colored lenses likely also depends upon second-stage ‘color-opponent’ mechanisms that compute sums and differences of cone signals." Not sure precisely what that means, but my guess is that the visual system is used to certain 'ratios' and contrasts of color frequencies. When the visual field is biased in some consistent way (e.g., light of a particular color, tint, etc.), the visual system automatically compensates by "recalculating" the ratios based on how much they deviate from normal conditions, trying to achieve normality of color perception utilizing a more limited palette of colors reaching the visual field.
Given all that, what's remarkable to me is that some people
instantly see pink/white sneakers. It is as if their visual system immediately concludes that there is a cyan tint to the photo and adapts immediately. No long-term wearing of tinted glasses necessary!