Reason behind so called Optical illusion or Simultaneous contrast

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Discussion Overview

The discussion revolves around the phenomenon of simultaneous contrast, where two blocks of the same color appear different depending on their background. Participants explore the underlying reasons for this effect, considering both physics and visual perception.

Discussion Character

  • Debate/contested
  • Conceptual clarification

Main Points Raised

  • Some participants seek literature on the physics behind simultaneous contrast and its visual implications.
  • One participant suggests that the phenomenon may be more related to biology and visual perception rather than physics.
  • A reference to "Basic Vision: an introduction to visual perception" is provided, explaining that retinal ganglion cells and lateral inhibition contribute to the perception of color differences.
  • Another participant questions whether imaging the blocks with a camera would yield the same RGB values, indicating a desire for a physical explanation of the phenomenon.
  • Some participants assert that there is no physics involved, emphasizing the role of brain processing in visual perception.
  • There is a request for further comments and insights on the topic from other participants.

Areas of Agreement / Disagreement

Participants express differing views on whether the phenomenon is primarily a matter of physics or visual perception, indicating that multiple competing perspectives remain without consensus.

Contextual Notes

Some claims rely on assumptions about the nature of visual processing and the limitations of imaging technology, which are not fully explored in the discussion.

shashipoddar1
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Hello everyone,

I am really looking out for some literature which has reported the physics behind the occurrence of the phenomena in which two blocks of same color seems different when kept in different background. I have attached an image which depicts the query in a very evident manner.

I would be really happy if you can kindly send me the reasons for this.

With best regards
 

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I would think that this is more a question of biology and visual perception than physics.
 
shashipoddar1 said:
Hello everyone,

I am really looking out for some literature which has reported the physics behind the occurrence of the phenomena in which two blocks of same color seems different when kept in different background. I have attached an image which depicts the query in a very evident manner.

I would be really happy if you can kindly send me the reasons for this.

With best regards

According to "Basic Vision: an introduction to visual perception" by Snowden et. al., the underlying reason is that the last layer of cells in your eye, the retinal ganglion cells, perform some intermediate optical processing prior to the next stage of vision- the lateral geniculate nucleus.

The retinal ganglion cells signal the presence of edges or rapid changes within their visual field, and are classified as either 'on-center' or 'off center', depending on what happens to the firing rate when light hits the center of the visual field. Each retinal ganglion cell has concentric and antagonistic receptive fields to accomplish this function- the phenomenon is called 'lateral inhibition', and is responsible for the illusion you showed in addition to a few others: the Hermann grid and the Craik-O'Brien-Cornsweet illusion.
 
I very well agree to your reasons given for the phenomena, but suppose when i image this through camera it should have given me the same RGB value at center boxes. But does this really occur. I am really looking out for the physics behind this if it has been quoted anywhere.
 
There isn't any physics behind it. It's about how our brains process things.
 
shashipoddar1 said:
Hello everyone,

I am really looking out for some literature which has reported the physics behind the occurrence of the phenomena in which two blocks of same color seems different when kept in different background. I have attached an image which depicts the query in a very evident manner.

I would be really happy if you can kindly send me the reasons for this.

With best regards

Can somebody else please comment on this phenomena..??
 
shashipoddar1 said:
<snip>suppose when i image this through camera it should have given me the same RGB value at center boxes. But does this really occur. <snip>

Suppose you try it and tell us.
 

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