After reading @Catherine0505's comment, it made much more sense to me why we would perceive A and B as having different colors. To me, the cylinder and its shadow are a detail that I wrote off as just being part of the scene, and I focused more on the checkerboard pattern on the board. The four darker surrounding squares of square B also immediately led me to the conclusion that A and B were differently colored.
cchendyc
I guess the color of the area b could also depend on the materials/textures/colors of the cylinder and the checkerboard, as they can all affect irradiance, while area a is only affected by the checkerboard and the light source.
sydkar
Discounting the illuminant is a cool phenomenon that has led to many of the common illusions we see today. This is one of the explanations scientists have used to explain the blue-black/white-gold dress debate from a few years ago. People's perception differed based on what lighting they thought the picture was taken in
abaqai
This phenomenon is very interesting especially when it comes to rendering images. Even though A and B are the same color, the image still looks "realistic" in terms of the shadows. Does this mean that when rendering an image like this, we don't account for the difference in received lighting for both A and B and just leave it up the optical illusion to differentiate the two.
JefferyYC
We can think of this phenomenon this way: human perceive the proportion of light, not the total light, reflected by the object. Therefore although A and B reflect the same amount of light, since B's environment has less illumination, it reflects more proportion of it, and appears whiter. When rendering, I think we should still model the reflectance of the surface as it is, and our brain would help us perceive the true color.
NicholasDrian
This reminds me of the warmth adjustment on cameras. It is interesting how in some lightings, a white wall looks red on camera, and other lightings make it look blue; but to a human, it always look white.
adityaramkumar
I wonder if without the cylindrical green object, we would still perceive the B to be lighter than A? Or put otherwise, what is the minimal set of objects that we need to make sure this illusion works the way it does currently?
melodysifry
If the perspective of this image and position of the green object were such that there was a black square right next to a white square and the shadow was only falling on the white square, I wonder whether we would still perceive such a difference in color between the white and black square. In other words, if square A and square B were right next to each other, perhaps with a sharper shadow so that the shadow stops right at the edge between A and B but they were still within the context of a checkerboard, would we still perceive a difference between the two colors?
somaniarushi
I have to wonder if modern cameras or modelling software employs this trick of the mind to cut down on shading sometimes. If we're going to perceive something as darker, is there any modern technique that takes advantage of this phenomena?
After reading @Catherine0505's comment, it made much more sense to me why we would perceive A and B as having different colors. To me, the cylinder and its shadow are a detail that I wrote off as just being part of the scene, and I focused more on the checkerboard pattern on the board. The four darker surrounding squares of square B also immediately led me to the conclusion that A and B were differently colored.
I guess the color of the area b could also depend on the materials/textures/colors of the cylinder and the checkerboard, as they can all affect irradiance, while area a is only affected by the checkerboard and the light source.
Discounting the illuminant is a cool phenomenon that has led to many of the common illusions we see today. This is one of the explanations scientists have used to explain the blue-black/white-gold dress debate from a few years ago. People's perception differed based on what lighting they thought the picture was taken in
This phenomenon is very interesting especially when it comes to rendering images. Even though A and B are the same color, the image still looks "realistic" in terms of the shadows. Does this mean that when rendering an image like this, we don't account for the difference in received lighting for both A and B and just leave it up the optical illusion to differentiate the two.
We can think of this phenomenon this way: human perceive the proportion of light, not the total light, reflected by the object. Therefore although A and B reflect the same amount of light, since B's environment has less illumination, it reflects more proportion of it, and appears whiter. When rendering, I think we should still model the reflectance of the surface as it is, and our brain would help us perceive the true color.
This reminds me of the warmth adjustment on cameras. It is interesting how in some lightings, a white wall looks red on camera, and other lightings make it look blue; but to a human, it always look white.
I wonder if without the cylindrical green object, we would still perceive the B to be lighter than A? Or put otherwise, what is the minimal set of objects that we need to make sure this illusion works the way it does currently?
If the perspective of this image and position of the green object were such that there was a black square right next to a white square and the shadow was only falling on the white square, I wonder whether we would still perceive such a difference in color between the white and black square. In other words, if square A and square B were right next to each other, perhaps with a sharper shadow so that the shadow stops right at the edge between A and B but they were still within the context of a checkerboard, would we still perceive a difference between the two colors?
I have to wonder if modern cameras or modelling software employs this trick of the mind to cut down on shading sometimes. If we're going to perceive something as darker, is there any modern technique that takes advantage of this phenomena?