It looks like this Japanese manga girl has one blue eye and one gray eye. In fact, both eyes are exactly the same shade of gray. The girl’s right eye only looks the same as the turquoise hair clip because of the reddish context....[More]
EYE SHADOW
It looks like this Japanese manga girl has one blue eye and one gray eye. In fact, both eyes are exactly the same shade of gray. The girl’s right eye only looks the same as the turquoise hair clip because of the reddish context. Part of the process of seeing color is that three different kinds of photoreceptors in the eye are tuned to three overlapping families of color: red, green and blue (which are activated by visible light of long, medium and short wavelengths). These signals are then instantaneously compared with signals from nearby regions in the same scene. As the signals are passed along to higher and higher processing centers in the brain, they continue to be compared with larger and larger swaths of the surrounding scene. This “opponent process,” as scientists call it, means that color and brightness are always relative.
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Akiyoshi Kitaoka
RED RINGS
This image by Kitaoka contains a number of blue-green circular structures. The red rings are purely a creation of your brain.
A process called color constancy makes an object look the same under different lighting conditions, even though the color of the light reflecting from the object is physically different....[More]
RED RINGS
This image by Kitaoka contains a number of blue-green circular structures. The red rings are purely a creation of your brain.
A process called color constancy makes an object look the same under different lighting conditions, even though the color of the light reflecting from the object is physically different. Color constancy is an incredibly important process that allows us to recognize objects, friends and family both in the firelight of the cave and in the bright sun of the savanna.
Because the rings here are drawn in shades of blue, the brain mistakenly assumes that the image is illuminated by blue light and that the physically gray rings inside the blue structures must therefore be reddish. The visual system subtracts the blue “ambient lighting” from the gray rings, and gray minus blue results in a pastel red color.
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Akiyoshi Kitaoka
MULTICOLORED RINGS
Here is another example of how the brain determines color depending on the context. In the bull’s-eye structures in the top half of the checkerboard, the center rings look either green or blue, but they are all the same color (turquoise)....[More]
MULTICOLORED RINGS
Here is another example of how the brain determines color depending on the context. In the bull’s-eye structures in the top half of the checkerboard, the center rings look either green or blue, but they are all the same color (turquoise). The center rings in the bottom half of the checkerboard are all the same shade of yellow. Unlike the previous images, this type of color illusion is difficult to explain by an opponent process because the apparent color of the rings is more similar than dissimilar to the background.
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Akiyoshi Kitaoka
WHITE'S EFFECT
In 1979 Michael White of the Tasmanian College of Advanced Education described an illusion that changed everything in visual science. The gray bars on the left look brighter than the gray bars on the right....[More]
WHITE'S EFFECT
In 1979 Michael White of the Tasmanian College of Advanced Education described an illusion that changed everything in visual science. The gray bars on the left look brighter than the gray bars on the right. In fact, all the gray bars are physically identical. Before White discovered this effect, all brightness illusions were thought to result from opponent processes—that is, a gray object should look dark when surrounded by light and light when surrounded by dark. But in this illusion the lighter-looking gray bars are surrounded by white stimuli, and the darker-looking gray bars are surrounded by black. The brain mechanisms underlying White’s effect remain unknown.
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Akiyoshi Kitaoka
YES! Send me a free issue of Scientific American with no obligation to continue the subscription. If I like it, I will be billed for the one-year subscription.
This illusion is not an opponent process, but rather appears to rely on blending. The yellow circular lines are thin. Anything on the scale of a pixel or so is not perceived very well by itself and gets blended with the surrounding colors to build a sense of the complete shape, and that means the structures combine red and yellow to make orange or blue and yellow to make more of a cyan color. The illusion is not sustained as well if you copy the image and paste it into a paint program and zoom in.
However, when zooming in on the image above, it becomes obvious that the yellow circles are not "pure" yellow in pixel color anyway. The image has possibly been reduced in size from the original by a standard image resizing algorithm. The image processing program performed two steps. The first is a "blur" step, contributing aspects of the neighboring pixels to the current pixel, and then a down sampling step, which removes some of the pixels so that the image is smaller. This prevents massive distortions in the overall image representation, but it means that if you were to use an RGB sampler on an average pixel in the "yellow" lines, they are not yellow at all. They range as some fuzzy blend of the original yellow with the background. Granted, when zoomed in, the lines look more yellow than they do at the scale above, so this is probably more about testing the resolution of color distinction than anything else.
In the third example of concentric same-colored circles, I experience a secondary effect of the color differences - in every bulleye, the inner circles, the ones appearing brighter, they are standing off the page, very much in the foreground, while the rest fades back into the background, creating a vivid, for me anyway, 3D effect. Somewhat related, read the The Art of Color by Johannes Itten if you can find it - color is personal.
I echo the comments of Shade1974. I zoomed in on the images at the pixel level and its clear that the captions that go along with the images are misleading. For instance, in the first image the eyes are, in fact, substantially different colors. This is clear when one zooms in at the pixel level, taking 'context' out of the equation.
5. David Illig
in reply to (Parentheses)01:32 AM 4/27/11
Examination of the color values of the girl's eyes with Adobe Photoshop reveals that both eyes are the same shade of gray. They each measure R=127, G=127, B=127.
Re photo 4 of 4: Depends on what you mean by "surrounded." The gray strips on the left side are surrounded by white horizontally, but black in the vertical direction; and vice-versa on the right. To my eye, on the left the black sections above and below the gray areas IN THE SAME BAR are more prominent than the SEPARATE white bars on either side, so makes sense to me that the gray midsections of each bar look lighter than the corresponding gray midsections on the right (where the surrounds and the effect are reversed). This is a matter of gestalts: each bar appears to me as a single gestalt, despite the alter(n)ation of tones; whereas any triplet of 3 bars that has the striped (and therefore geometrically different) bar in the middle is not a gestalt; or cannot be seen as such so easily. Has everyone these days forgotten the tremendously important work of the gestalt psychologists in the '20s and '30s of the last century? And for that matter, the work of Edwin Land on perceived color as a field phenomenon, so ably reported in this journal in the '50s and maybe later?
Did anyone consult a color-blind person for their perception? Several of these don't have that affect on me.
I'm red-green-pastel colorblind in the severe category.
Finding the dropped thing on the floor has always been easy for me. I never look for the color. My world has always been controlled by geometry. The shape of things to come.
BTW, my favorite color is burnt orange. Explain that.
The thing I see is that I have to read the comments before I know what to look for. This might not seem helpful until you realize I'm R/B color blind. So both eyes look grey to me. However, the left eye seems a lighter shade of grey.
This article and slideshow would be significantly more interesting if the pictures were not saved in badly compressed JPEG and therefore colourblurred. Some of the captions are now lying (for instance http://www.scientificamerican.com/slideshow.cfm?id=colors-out-of-space&photo_id=4B011270-D5EA-1D86-0DA789FDDD994CB7), because the JPEG will blur the colours a bit if you compress it like that. (Load it and check the colour values. The colours are _not_ the same, although they probably were once.) Could we have them in PNG instead?
What is the difference between White's effect (slide 4)--which allegedly "changed everything in visual science" in 1979--and the von Bezold spreading effect (1874)? http://en.wikipedia.org/wiki/Bezold_effect
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12 Comments
Add CommentThis illusion is not an opponent process, but rather appears to rely on blending. The yellow circular lines are thin. Anything on the scale of a pixel or so is not perceived very well by itself and gets blended with the surrounding colors to build a sense of the complete shape, and that means the structures combine red and yellow to make orange or blue and yellow to make more of a cyan color. The illusion is not sustained as well if you copy the image and paste it into a paint program and zoom in.
Reply | Report Abuse | Link to thisHowever, when zooming in on the image above, it becomes obvious that the yellow circles are not "pure" yellow in pixel color anyway. The image has possibly been reduced in size from the original by a standard image resizing algorithm. The image processing program performed two steps. The first is a "blur" step, contributing aspects of the neighboring pixels to the current pixel, and then a down sampling step, which removes some of the pixels so that the image is smaller. This prevents massive distortions in the overall image representation, but it means that if you were to use an RGB sampler on an average pixel in the "yellow" lines, they are not yellow at all. They range as some fuzzy blend of the original yellow with the background. Granted, when zoomed in, the lines look more yellow than they do at the scale above, so this is probably more about testing the resolution of color distinction than anything else.
In the third example of concentric same-colored circles, I experience a secondary effect of the color differences - in every bulleye, the inner circles, the ones appearing brighter, they are standing off the page, very much in the foreground, while the rest fades back into the background, creating a vivid, for me anyway, 3D effect. Somewhat related, read the The Art of Color by Johannes Itten if you can find it - color is personal.
Reply | Report Abuse | Link to thisThe above comment was for Image 3/4. It seems our comments aren't slide specific.
Reply | Report Abuse | Link to thisI echo the comments of Shade1974. I zoomed in on the images at the pixel level and its clear that the captions that go along with the images are misleading. For instance, in the first image the eyes are, in fact, substantially different colors. This is clear when one zooms in at the pixel level, taking 'context' out of the equation.
Reply | Report Abuse | Link to thisExamination of the color values of the girl's eyes with Adobe Photoshop reveals that both eyes are the same shade of gray. They each measure R=127, G=127, B=127.
Reply | Report Abuse | Link to thisRe photo 4 of 4: Depends on what you mean by "surrounded." The gray strips on the left side are surrounded by white horizontally, but black in the vertical direction; and vice-versa on the right. To my eye, on the left the black sections above and below the gray areas IN THE SAME BAR are more prominent than the SEPARATE white bars on either side, so makes sense to me that the gray midsections of each bar look lighter than the corresponding gray midsections on the right (where the surrounds and the effect are reversed). This is a matter of gestalts: each bar appears to me as a single gestalt, despite the alter(n)ation of tones; whereas any triplet of 3 bars that has the striped (and therefore geometrically different) bar in the middle is not a gestalt; or cannot be seen as such so easily. Has everyone these days forgotten the tremendously important work of the gestalt psychologists in the '20s and '30s of the last century? And for that matter, the work of Edwin Land on perceived color as a field phenomenon, so ably reported in this journal in the '50s and maybe later?
Reply | Report Abuse | Link to thisDid anyone consult a color-blind person for their perception? Several of these don't have that affect on me.
Reply | Report Abuse | Link to thisI'm red-green-pastel colorblind in the severe category.
Finding the dropped thing on the floor has always been easy for me. I never look for the color. My world has always been controlled by geometry. The shape of things to come.
BTW, my favorite color is burnt orange. Explain that.
The thing I see is that I have to read the comments before I know what to look for.
Reply | Report Abuse | Link to thisThis might not seem helpful until you realize I'm R/B color blind. So both eyes look grey to me.
However, the left eye seems a lighter shade of grey.
Oops, I erred: I'm red green colorblind. I claim red blue by mistake. Sorry.
Reply | Report Abuse | Link to thisBut someone asked about color blind folk, so here it is.
Ok, I call scientific fraud on this. There is little sense to this claim and if anything, they're saying you're all color blind, which you aren't.
Reply | Report Abuse | Link to thisThis article and slideshow would be significantly more interesting if the pictures were not saved in badly compressed JPEG and therefore colourblurred. Some of the captions are now lying (for instance http://www.scientificamerican.com/slideshow.cfm?id=colors-out-of-space&photo_id=4B011270-D5EA-1D86-0DA789FDDD994CB7), because the JPEG will blur the colours a bit if you compress it like that. (Load it and check the colour values. The colours are _not_ the same, although they probably were once.)
Reply | Report Abuse | Link to thisCould we have them in PNG instead?
What is the difference between White's effect (slide 4)--which allegedly "changed everything in visual science" in 1979--and the von Bezold spreading effect (1874)?
Reply | Report Abuse | Link to thishttp://en.wikipedia.org/wiki/Bezold_effect