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The title is horribly worded, but I have no idea how to otherwise title it.

Basically, the idea behind these special eyes is that they would be structured much like real-life compound eyes, but the first half of the ommatidia tunnel is mostly filled with a black mass that would absorb any light it touches, meaning only light reflected from a narrow angle from the front of the ommatidia would get to the second half where all the photoreceptor cells lie. These photoreceptor cells would then discern the colour of that light. Repeat this for each ommatidia in the eyes and you get a pixelart-like image, composed of individual hexagonal "pixels". The organisms would use multiple much smaller simple eyes (ocelli) to accurately detect distance.

The organisms in question would be mostly between the size of a mini Golden Retriever and a horse. The main supposed benefit of this eye type would be that the simple nature of a pixelated image would make the amount of brain space required to process it pretty small while allowing vision in all available degrees without the atrocious peripheral vision that human-like eyes have.

My main question is, is there something about the nature of light that I am missing that would make this unreasonable, impractical or otherwise outside of the realm of possibility?

Thanks!

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    $\begingroup$ "The simple nature of a pixelated image would make the amount of brain space required to process it pretty small": That depends on the number of pixels, doesn't it? When you look at any modern TV, you see a pixelated image. Does the pixelated nature of the image make it in any important way different from a non-pixelated painting? And if you reduce the number of pixels sufficiently to make the processing easier, you also decrease resolving power so much that the organism would be legally blind. $\endgroup$
    – AlexP
    Dec 31, 2022 at 21:14
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    $\begingroup$ Human eyes do not output a matrix of pixels. The most charitable interpretation of that number is that a 13 megapixel image covering the entire field of view of an eye would appear continuous; which is not really true, but it is not very far from truth. (25 megapixels would be closer to the truth, 50 megapixels would be ideal.) The way human vision works, it has a resolving power of about 1 arc-minute in the center of the field; the eyes scan autonomously (in saccades) the field of view, thus enabling the brain to build a mental map. $\endgroup$
    – AlexP
    Dec 31, 2022 at 21:33
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    $\begingroup$ Are you looking specifically for pixelated vision or for reduced brain processing? If the former, you might want to consider giving your organisms a modified brain. This brain can only see images in pixels. The brain is a neuroplastic organ and it might be easier to attribute deviant sight to the brain than to adapted eyes. $\endgroup$
    – Theresa Kay
    Jan 1 at 5:50
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    $\begingroup$ In regards to the question: I upvoted it because it's an interesting concept. If you're looking to rephrase the title, maybe consider "Would pixelated vision be possible?" or "Is it plausible to have eyes that give pixelated vision?" $\endgroup$
    – Theresa Kay
    Jan 1 at 5:52
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    $\begingroup$ Is there any particular reason that you're considering compound eyes with lots of photoreceptor cells and only some small number n of pixels, instead of just having simple eyes with n photoreceptor cells? The latter option seems much simpler and more plausible, and I'm having trouble thinking of any disadvantages. $\endgroup$
    – Tanner Swett
    Jan 1 at 11:21

3 Answers 3

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. . . meaning only light reflected from a narrow angle from the front of the ommatidia would get to the second half where all the photoreceptor cells lie.

An obvious difficulty is that this kind of eye wastes most of the light that reaches it. It is thus a competitive disadvantage compared to a conventional compound or human-like eye, simply because a creature with it is much less able to see in poor light. This does not seem like a good trade-off against the cost of some nerve tissue for visual processing.

Using a hypothetical kind of cone cell that is as sensitive as a rod cell will not solve this problem. Rods are only about 100 times more sensitive than cones. If your eye elements accept light over an angle of one degree, (1/57th of a radian), you're only taking in about (1/57*57) = 0.03% of the light that a human-style eye (with an angle of view of about a square radian) would get. You're getting about a thirtieth of the effective light of a conventional eye, with about forty times worse angular resolution.

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  • $\begingroup$ Counterpoint: couldn't a type of cell that is both as sensitive to light as rod cells and as perceptive to light as cone cells work around this? $\endgroup$
    – AlexanderRosary
    Dec 31, 2022 at 21:48
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    $\begingroup$ @AlexanderRosary: No. See the added paragraph of the answer. $\endgroup$
    – John Dallman
    Dec 31, 2022 at 23:28
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    $\begingroup$ Thanks for the answer! $\endgroup$
    – AlexanderRosary
    Jan 1 at 9:36
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The image might be pixelated, but vision will not be.

Our brains do a huge amount of processing of the "raw data" that comes from our eyes, and presumably, your organisms will do the same. Even if the raw data from the eyes was pixelated, it seems likely that the brain would do something to remove this pixelation, like maybe incorporating information from the very recent past to remove the pixelation. The most I can imagine happening is that if an organism briefly glances at an object then moves its eyes away, the image it sees might be pixelated, but in general, the organism's vision will not be pixelated.

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    $\begingroup$ +1 My favorite movie quote on this Stack applies. From The Hunt for Red October, "Can you launch an ICBM horizontally?" "Sure! Why would you want to?" By definition all sight is pixelated because the number of rods/cones in any eye is finite. The number of nerves in the optic nerve is also finite. Thus, the fact that something I'm looking at doesn't look pixelated is exactly what you've explained. Why bother evolving to see non-pixelated information? Well, I'd hate for the predator to hide between the pixels. $\endgroup$
    – JBH
    Jan 1 at 6:27
  • $\begingroup$ Thanks for the feedback @Robert! The way these guys are set up is precisely that the brain doesn't really do any extra processing of the data it gets from the eyes, it just sees an image composed of "hexagonal pixels" $\endgroup$
    – AlexanderRosary
    Jan 1 at 9:33
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    $\begingroup$ @AlexanderRosary: Yes, but the point of this answer is that it's unlikely that evolution would produce an organism with vision like that without synthesizing those pixels into an image of the world. It's always hard to imagine what it would be like to think as a creature different from oneself, but I'd be really surprised if the pixel boundaries would actually be sharp in their mental image, especially with some visible shape finer than the resolution of their eye. (Why have the brainpower to imagine / visualize images sharper than the eye can generate?) $\endgroup$
    – Peter Cordes
    Jan 1 at 11:50
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    $\begingroup$ @AlexanderRosary Not all of the photoreceptor cells will fire in sync, so the brain will have to do some sort of processing to get an actual image out of the raw signal. This processing would involve using information from the recent past, and since this processing already exists, its seems like it would be evolutionarily advantageous to do slightly more of it to get a sharper image. $\endgroup$
    – Robert
    Jan 1 at 13:37
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Broadly yes, they would, unless you can show an objection…

What 'compound-like' means is up to you.

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    $\begingroup$ Can you expand on this? $\endgroup$
    – Joachim
    Jan 1 at 22:52
  • $\begingroup$ expand. This is a comment, not an answer. $\endgroup$
    – Hukk2010
    Apr 2 at 6:52

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