Hermann Grid Illusion | New Version | Springer - Subjective Diagonals | Simultaneous Contrast | Checker-Shadow Illusion | Koffka Ring | Ehrenstein's Pattern | Bezold Effect: Color Assimilation
For an explanation of many of the contrast phenomena, see Context Effects.
While scanning over the left matrix you probably see gray blobs in the intersections of the black crosses formed by the white squares (vice versa for the right matrix). These blobs can be explained by reference to receptive fields and lateral inhibition.
Note: Concerning the Hermann grid, its history and follow-up, see see Bernd Lingelbach and Walter Ehrenstein's recent review (in German) in: www.leinroden.de/304herfold.htm
Try counting the black dots! :)
Capillary gray lines are visible on the diagonals.
Place
your mouse pointer over the image in order to envision the illusion!
The small squares within the larger ones are all exactly the same color gray (just move your mouse over the image and convince yourself). As you can see, the lightness of the background effects the way in which we perceive the lightness of the small squares: the very left small square seems darker than the very right one. The perception of this kind of display is a result of lateral interactions.
In this illusion from E. H. Adelson called checker-shadow illusion, the squares marked A and B are the same shade of gray (we checked that in an image processing program). Like in the simultaneous contrast example above, the environment of a square determines its perceived lightness.
Andrew Dyk created an animated version of this illusion (animated GIF; in a player application you can run it in an endless loop) . He wrote: "Now one can see the grey levels are the same. I'm sorry but I didn't believe it at first until I brought it into Photoshop."
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Place your mouse pointer over the image in order to envision the illusion! |
The gray ring on the black and gray or black and white ground appears to be uniformly gray. However, if you divide the ring into two parts, the gray color appears to be different depending on the color of the ground.
In the first image the non-existing circles appear to be very bright.
In the next image they seem to be very dark.
The blue or yellow areas adjacent to the green triangles (on the left side)
influence the appearance of the green triangles. The yellow makes the green
appear lighter and the blue makes the green appear darker. Moreover, it is
as if a blending of colors occurs - the green triangles have a light bluish
tinge in the yellow environment. This phenomenon is the opposite of a contrast
effect where one expects nearby colors to accentuate the differences between
adjacent areas.
(You can notice the same effects with different colors on the right side of
the image)
Animated version of the Bezold effect
