Pupil Shape in the Animal Kingdom - Revision history

Leiyu: /* Limitations of using diffraction-limited optics and pupil models in this work */

2024-12-13T19:01:17Z

Limitations of using diffraction-limited optics and pupil models in this work

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	===Limitations of using diffraction-limited optics and pupil models in this work===		===Limitations of using diffraction-limited optics and pupil models in this work===
	While diffraction can affect optical systems, when it comes to the human or animal ~~eye~~, especially regarding how light enters through the pupil, diffraction issue is not the major concern, instead, the chromatic aberration in cornea and lens is. Chromatic aberration occurs when different wavelengths of light are focused at different points, leading to color fringing around objects. This effect is more pronounced in the cornea due to its curved surface and varying refractive indices for different wavelengths.		While diffraction can affect optical systems, when it comes to the human or animal eyes, especially regarding how light enters through the pupil, diffraction issue is not the major concern, instead, the chromatic aberration in cornea and lens is. Chromatic aberration occurs when different wavelengths of light are focused at different points, leading to color fringing around objects. This effect is more pronounced in the cornea due to its curved surface and varying refractive indices for different wavelengths.

	== Conclusions ==		== Conclusions ==

Leiyu at 18:59, 13 December 2024

2024-12-13T18:59:00Z

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	Following is a link to a video taken of a Mantis shrimp in Monad Shoal, Malapascua, Philippines. The eye movements can be seen: https://www.youtube.com/watch?v=WnkQmnUcKyA		Following is a link to a video taken of a Mantis shrimp in Monad Shoal, Malapascua, Philippines. The eye movements can be seen: https://www.youtube.com/watch?v=WnkQmnUcKyA

			===Limitations of using diffraction-limited optics and pupil models in this work===
			While diffraction can affect optical systems, when it comes to the human or animal eye, especially regarding how light enters through the pupil, diffraction issue is not the major concern, instead, the chromatic aberration in cornea and lens is. Chromatic aberration occurs when different wavelengths of light are focused at different points, leading to color fringing around objects. This effect is more pronounced in the cornea due to its curved surface and varying refractive indices for different wavelengths.

	== Conclusions ==		== Conclusions ==

Leiyu at 17:36, 13 December 2024

2024-12-13T17:36:24Z

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	The midband of the mantis shrimp eye is the only portion with multiple photoreceptor types. One study [9] showed that although they have a huge resolution in terms of sampled wavelengths, they are only effectively able to distinguish colours up to 25nm apart in the visible light spectrum. In order to investigate whether chromatic aberration plays a part in their colour vision like the cuttlefish, the triple-slit pupil was simulated in the same way as above. Also, a triple parallel slit pupil was simulated out of academic interest, although no animal is known to us to have this pupil shape.		The midband of the mantis shrimp eye is the only portion with multiple photoreceptor types. One study [9] showed that although they have a huge resolution in terms of sampled wavelengths, they are only effectively able to distinguish colours up to 25nm apart in the visible light spectrum. In order to investigate whether chromatic aberration plays a part in their colour vision like the cuttlefish, the triple-slit pupil was simulated in the same way as above. Also, a triple parallel slit pupil was simulated out of academic interest, although no animal is known to us to have this pupil shape.

	[[File: Multiple slit.png\| 800px\|thumb\|center\|Figure 5. Multiple slit pupil PSF and resulting OI of a gridline scene. The upper set of images is close to the real mantis shrimp pupil, whilst the lower set is a tri-parallel slit simulated out of curiosity. Chromatic aberration is seen mostly in the second, suggesting that is the optimal design if chromatic aberration is desired]]		[[File: Multiple slit.png\| 800px\|thumb\|center\|Figure 7. Multiple slit pupil PSF and resulting OI of a gridline scene. The upper set of images is close to the real mantis shrimp pupil, whilst the lower set is a tri-parallel slit simulated out of curiosity. Chromatic aberration is seen mostly in the second, suggesting that is the optimal design if chromatic aberration is desired]]

	It can be seen that for the multiple slit colinear pupil, there is actually not much difference to the single horizontal slit. No significant chromatic aberrations can be seen, suggesting that it does not use chromatic aberration for colour vision like the cuttlefish; it instead relies on the multiple photoreceptor types.		It can be seen that for the multiple slit colinear pupil, there is actually not much difference to the single horizontal slit. No significant chromatic aberrations can be seen, suggesting that it does not use chromatic aberration for colour vision like the cuttlefish; it instead relies on the multiple photoreceptor types.

WLP-LY-RS: /* References */

2024-12-13T16:04:42Z

References

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	==References==		==References==
	[1]M. S. Banks, W. W. Sprague, J. Schmoll, J. A. Q. Parnell, and G. D. Love, “Why do animal eyes have pupils of different shapes?,” Science Advances, vol. 1, no. 7, p. e1500391, Aug. 2015, doi: https://doi.org/10.1126/sciadv.1500391.		[1]M. S. Banks, W. W. Sprague, J. Schmoll, J. A. Q. Parnell, and G. D. Love, “Why do animal eyes have pupils of different shapes?,” Science Advances, vol. 1, no. 7, p. e1500391, Aug. 2015, doi: https://doi.org/10.1126/sciadv.1500391.

	[2]Min Su Kim et al., “Feline eye–inspired artificial vision for enhanced camouflage breaking under diverse light conditions,” Science Advances, vol. 10, no. 38, Sep. 2024, doi: https://doi.org/10.1126/sciadv.adp2809.		[2]Min Su Kim et al., “Feline eye–inspired artificial vision for enhanced camouflage breaking under diverse light conditions,” Science Advances, vol. 10, no. 38, Sep. 2024, doi: https://doi.org/10.1126/sciadv.adp2809.

	[3]M. Kim et al., “Cuttlefish eye–inspired artificial vision for high-quality imaging under uneven illumination conditions,” Science Robotics, vol. 8, no. 75, Feb. 2023, doi: https://doi.org/10.1126/scirobotics.ade4698.		[3]M. Kim et al., “Cuttlefish eye–inspired artificial vision for high-quality imaging under uneven illumination conditions,” Science Robotics, vol. 8, no. 75, Feb. 2023, doi: https://doi.org/10.1126/scirobotics.ade4698.

	[4]S. Chang, D.-J. Kong, and Young Min Song, “Advanced visual components inspired by animal eyes,” Nanophotonics, vol. 0, no. 0, Mar. 2024, doi: https://doi.org/10.1515/nanoph-2024-0014.		[4]S. Chang, D.-J. Kong, and Young Min Song, “Advanced visual components inspired by animal eyes,” Nanophotonics, vol. 0, no. 0, Mar. 2024, doi: https://doi.org/10.1515/nanoph-2024-0014.

	[5]“The Science Behind Cat Eyes,” Small Cat Advocacy and Research (SCAR), Sep. 28, 2021. https://scar.lk/the-science-behind-cat-eyes/ (accessed Dec. 11, 2024).		[5]“The Science Behind Cat Eyes,” Small Cat Advocacy and Research (SCAR), Sep. 28, 2021. https://scar.lk/the-science-behind-cat-eyes/ (accessed Dec. 11, 2024).

	[6]“Diversity in Pupil Dimensions across the Animal Kingdom – An Aesthetic Creation with Visual Significance,” Vision Science Academy, Oct. 01, 2020. https://visionscienceacademy.org/diversity-in-pupil-dimensions-across-the-animal-kingdom-an-aesthetic-creation-with-visual-significance/		[6]“Diversity in Pupil Dimensions across the Animal Kingdom – An Aesthetic Creation with Visual Significance,” Vision Science Academy, Oct. 01, 2020. https://visionscienceacademy.org/diversity-in-pupil-dimensions-across-the-animal-kingdom-an-aesthetic-creation-with-visual-significance/

	[7]L. M. Mäthger, R. T. Hanlon, J. Håkansson, and D.-E. Nilsson, “The W-shaped pupil in cuttlefish (Sepia officinalis): Functions for improving horizontal vision,” Vision Research, vol. 83, pp. 19–24, May 2013, doi: https://doi.org/10.1016/j.visres.2013.02.016.		[7]L. M. Mäthger, R. T. Hanlon, J. Håkansson, and D.-E. Nilsson, “The W-shaped pupil in cuttlefish (Sepia officinalis): Functions for improving horizontal vision,” Vision Research, vol. 83, pp. 19–24, May 2013, doi: https://doi.org/10.1016/j.visres.2013.02.016.

	[8]T. W. Cronin, M. J. Bok, N. J. Marshall, and R. L. Caldwell, “Filtering and polychromatic vision in mantis shrimps: themes in visible and ultraviolet vision,” Philosophical Transactions of the Royal Society B: Biological Sciences, vol. 369, no. 1636, Feb. 2014, doi: https://doi.org/10.1098/rstb.2013.0032.		[8]T. W. Cronin, M. J. Bok, N. J. Marshall, and R. L. Caldwell, “Filtering and polychromatic vision in mantis shrimps: themes in visible and ultraviolet vision,” Philosophical Transactions of the Royal Society B: Biological Sciences, vol. 369, no. 1636, Feb. 2014, doi: https://doi.org/10.1098/rstb.2013.0032.

	[9]J. Morrison, “Mantis shrimp’s super colour vision debunked,” Nature, Jan. 2014, doi: https://doi.org/10.1038/nature.2014.14578.		[9]J. Morrison, “Mantis shrimp’s super colour vision debunked,” Nature, Jan. 2014, doi: https://doi.org/10.1038/nature.2014.14578.

	[10]A. L. Stubbs and C. W. Stubbs, “Spectral discrimination in color blind animals via chromatic aberration and pupil shape,” Proceedings of the National Academy of Sciences, vol. 113, no. 29, pp. 8206–8211, Jul. 2016, doi: https://doi.org/10.1073/pnas.1524578113.		[10]A. L. Stubbs and C. W. Stubbs, “Spectral discrimination in color blind animals via chromatic aberration and pupil shape,” Proceedings of the National Academy of Sciences, vol. 113, no. 29, pp. 8206–8211, Jul. 2016, doi: https://doi.org/10.1073/pnas.1524578113.

	[11]“How mantis shrimp make sense of the world \| NSF - National Science Foundation,” new.nsf.gov, Dec. 04, 2019. https://new.nsf.gov/news/how-mantis-shrimp-make-sense-world		[11]“How mantis shrimp make sense of the world \| NSF - National Science Foundation,” new.nsf.gov, Dec. 04, 2019. https://new.nsf.gov/news/how-mantis-shrimp-make-sense-world

WLP-LY-RS at 16:03, 13 December 2024

2024-12-13T16:03:44Z

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	These plots support our understanding of the behavior of predator animals. Many predators with vertical slit pupils are also nocturnal. During the day, their pupils constrict to a small area to limit the amount of light entering the eye. If their pupils were circular, the small aperture would cause significant diffraction, leading to a loss of visual clarity. However, the vertical slit pupil allows them to maintain good focus along one axis, despite the reduced aperture size, enabling them to retain functional vision even in bright conditions. This ability is particularly beneficial for nocturnal predators, allowing them to effectively navigate and hunt in varying lighting conditions.		These plots support our understanding of the behavior of predator animals. Many predators with vertical slit pupils are also nocturnal. During the day, their pupils constrict to a small area to limit the amount of light entering the eye. If their pupils were circular, the small aperture would cause significant diffraction, leading to a loss of visual clarity. However, the vertical slit pupil allows them to maintain good focus along one axis, despite the reduced aperture size, enabling them to retain functional vision even in bright conditions. This ability is particularly beneficial for nocturnal predators, allowing them to effectively navigate and hunt in varying lighting conditions.


	===Effect of W-shaped pupil on chromatic aberration===		===Effect of W-shaped pupil on chromatic aberration===

WLP-LY-RS at 16:01, 13 December 2024

2024-12-13T16:01:10Z

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	When comparing a slit pupil to a circular pupil of the same area, we observe that for a smaller aperture, the circular pupil leads to blurring across the entire scene. This occurs because diffraction becomes more pronounced in smaller apertures, causing the loss of sharp focus. In contrast, a slit pupil of the same area can retain focus along one axis. Specifically, for a vertical slit pupil, the image remains sharp along the vertical direction while blurring occurs along the horizontal axis.		When comparing a slit pupil to a circular pupil of the same area, we observe that for a smaller aperture, the circular pupil leads to blurring across the entire scene. This occurs because diffraction becomes more pronounced in smaller apertures, causing the loss of sharp focus. In contrast, a slit pupil of the same area can retain focus along one axis. Specifically, for a vertical slit pupil, the image remains sharp along the vertical direction while blurring occurs along the horizontal axis.

	[[File: Figure 1 vertical_vs_round .png\|~~900px~~\|thumb\|center\|Figure 3. Vertical pupil has enhanced features identification along the vertical direction compared with round pupil with the same size. (A) Round pupils in comparison with the vertical pupils with the same size (B) Point Spread Function of each pupil case. (C) Optical images of the grid scene. (D) Cone mosaic absorption of the optical image and (E) the horizontal integration of the absorption intensity. ]]		[[File: Figure 1 vertical_vs_round .png\|800px\|thumb\|center\|Figure 3. Vertical pupil has enhanced features identification along the vertical direction compared with round pupil with the same size. (A) Round pupils in comparison with the vertical pupils with the same size (B) Point Spread Function of each pupil case. (C) Optical images of the grid scene. (D) Cone mosaic absorption of the optical image and (E) the horizontal integration of the absorption intensity. ]]

	These plots support our understanding of the behavior of predator animals. Many predators with vertical slit pupils are also nocturnal. During the day, their pupils constrict to a small area to limit the amount of light entering the eye. If their pupils were circular, the small aperture would cause significant diffraction, leading to a loss of visual clarity. However, the vertical slit pupil allows them to maintain good focus along one axis, despite the reduced aperture size, enabling them to retain functional vision even in bright conditions. This ability is particularly beneficial for nocturnal predators, allowing them to effectively navigate and hunt in varying lighting conditions.		These plots support our understanding of the behavior of predator animals. Many predators with vertical slit pupils are also nocturnal. During the day, their pupils constrict to a small area to limit the amount of light entering the eye. If their pupils were circular, the small aperture would cause significant diffraction, leading to a loss of visual clarity. However, the vertical slit pupil allows them to maintain good focus along one axis, despite the reduced aperture size, enabling them to retain functional vision even in bright conditions. This ability is particularly beneficial for nocturnal predators, allowing them to effectively navigate and hunt in varying lighting conditions.
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	Cuttlefish are an interesting case in the animal kingdom. They are famous for their colorful displays and ability to dynamically camouflage themselves, yet they are actually monochromats, effectively colorblind. One paper [10] suggests they make use of chromatic aberration to distinguish between colours using their single photoreceptor type (at the cost of requiring more processing power behind their visual system).		Cuttlefish are an interesting case in the animal kingdom. They are famous for their colorful displays and ability to dynamically camouflage themselves, yet they are actually monochromats, effectively colorblind. One paper [10] suggests they make use of chromatic aberration to distinguish between colours using their single photoreceptor type (at the cost of requiring more processing power behind their visual system).

	[[File: Cuttlefish eye.png\| 200px\|thumb\|~~right~~\|Figure 4. The eye of a cuttlefish. Source: Adobe Stock]]		[[File: Cuttlefish eye.png\| 200px\|thumb\|center\|Figure 4. The eye of a cuttlefish. Source: Adobe Stock]]

	To test the theory that their unique W-shaped pupil produced chromatic aberrations, a custom aperture mask was created and resulting optical image generated with a gridline scene. In the case of a larger pupil size, clear vertical lines and slightly blurred horizontal lines are seen, as expected given its overall horizontal slit-like aspect ratio. Additionally, clear red colour fringing is seen in the vertical lines, supporting this theory that one purpose of their unique pupil shape is to produce chromatic aberrations on their cone mosaic.		To test the theory that their unique W-shaped pupil produced chromatic aberrations, a custom aperture mask was created and resulting optical image generated with a gridline scene. In the case of a larger pupil size, clear vertical lines and slightly blurred horizontal lines are seen, as expected given its overall horizontal slit-like aspect ratio. Additionally, clear red colour fringing is seen in the vertical lines, supporting this theory that one purpose of their unique pupil shape is to produce chromatic aberrations on their cone mosaic.
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	Furthermore, in 3D the W/U shape has the effect of being a vertical slit when viewed from the front, and a horizontal slit from the side. Potentially this could help the cuttlefish as an ambush predator, whilst still being able to scan for threats in the periphery.		Furthermore, in 3D the W/U shape has the effect of being a vertical slit when viewed from the front, and a horizontal slit from the side. Potentially this could help the cuttlefish as an ambush predator, whilst still being able to scan for threats in the periphery.

	[[File: W-shape pupil figure.png\| ~~900px~~\|thumb\|center\|Figure 5. W-shape pupil PSF and optical image of a grid scene. Upper figure has a 453px major axis length; lower figure has a 350px major axis length.]]		[[File: W-shape pupil figure.png\| 800px\|thumb\|center\|Figure 5. W-shape pupil PSF and optical image of a grid scene. Upper figure has a 453px major axis length; lower figure has a 350px major axis length.]]

	===Multiple-slit pupil: Mantis Shrimp===		===Multiple-slit pupil: Mantis Shrimp===

WLP-LY-RS at 16:00, 13 December 2024

2024-12-13T16:00:22Z

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	===Effect of W-shaped pupil on chromatic aberration===		===Effect of W-shaped pupil on chromatic aberration===
	~~[[File: Cuttlefish eye.png\| 150px\|thumb\|right\|Figure 4. The eye of a cuttlefish. Source: Adobe Stock]]~~

	Cuttlefish are an interesting case in the animal kingdom. They are famous for their colorful displays and ability to dynamically camouflage themselves, yet they are actually monochromats, effectively colorblind. One paper [10] suggests they make use of chromatic aberration to distinguish between colours using their single photoreceptor type (at the cost of requiring more processing power behind their visual system).		Cuttlefish are an interesting case in the animal kingdom. They are famous for their colorful displays and ability to dynamically camouflage themselves, yet they are actually monochromats, effectively colorblind. One paper [10] suggests they make use of chromatic aberration to distinguish between colours using their single photoreceptor type (at the cost of requiring more processing power behind their visual system).

			[[File: Cuttlefish eye.png\| 200px\|thumb\|right\|Figure 4. The eye of a cuttlefish. Source: Adobe Stock]]

	To test the theory that their unique W-shaped pupil produced chromatic aberrations, a custom aperture mask was created and resulting optical image generated with a gridline scene. In the case of a larger pupil size, clear vertical lines and slightly blurred horizontal lines are seen, as expected given its overall horizontal slit-like aspect ratio. Additionally, clear red colour fringing is seen in the vertical lines, supporting this theory that one purpose of their unique pupil shape is to produce chromatic aberrations on their cone mosaic.		To test the theory that their unique W-shaped pupil produced chromatic aberrations, a custom aperture mask was created and resulting optical image generated with a gridline scene. In the case of a larger pupil size, clear vertical lines and slightly blurred horizontal lines are seen, as expected given its overall horizontal slit-like aspect ratio. Additionally, clear red colour fringing is seen in the vertical lines, supporting this theory that one purpose of their unique pupil shape is to produce chromatic aberrations on their cone mosaic.

WLP-LY-RS at 15:58, 13 December 2024

2024-12-13T15:58:54Z

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	===Aperture===		===Aperture===
	The aperture represents the pupil shape and is modeled as a 201x201 matrix. In this matrix, ones indicate the regions where light can pass through (white), while zeros denote the areas where light is blocked (black).		The aperture represents the pupil shape and is modeled as a 201x201 matrix. In this matrix, ones indicate the regions where light can pass through (white), while zeros denote the areas where light is blocked (black).
	For the single-slit elliptical aperture, we can adjust both the size and the orientation of the ellipse (vertical or horizontal). For the multiple-slit aperture, we can modify the slit length, slit width, and the number of slits. For the w-shaped aperture, we intake the w-shape black and white image to generate the aperture matrix, and are able to change the size of it. In this case we make use of the wvfAperture function, modified slightly to allow non circularly-symmetric apertures in a new function wvfApertureNonCirc. We make use of the wavefront structure in the ISETCam code.		For the single-slit elliptical aperture, we can adjust both the size and the orientation of the ellipse (vertical or horizontal). For the multiple-slit aperture, we can modify the slit length, slit width, and the number of slits. For the w-shaped aperture, we intake the w-shape black and white image to generate the aperture matrix, and are able to change the size of it.

	===Point spread function and optical image===		===Point spread function and optical image===
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	===Effect of W-shaped pupil on chromatic aberration===		===Effect of W-shaped pupil on chromatic aberration===
			[[File: Cuttlefish eye.png\| 150px\|thumb\|right\|Figure 4. The eye of a cuttlefish. Source: Adobe Stock]]

	Cuttlefish are an interesting case in the animal kingdom. They are famous for their colorful displays and ability to dynamically camouflage themselves, yet they are actually monochromats, effectively colorblind. One paper [10] suggests they make use of chromatic aberration to distinguish between colours using their single photoreceptor type (at the cost of requiring more processing power behind their visual system).		Cuttlefish are an interesting case in the animal kingdom. They are famous for their colorful displays and ability to dynamically camouflage themselves, yet they are actually monochromats, effectively colorblind. One paper [10] suggests they make use of chromatic aberration to distinguish between colours using their single photoreceptor type (at the cost of requiring more processing power behind their visual system).

	~~[[File: Cuttlefish eye.png\| 200px\|thumb\|right\|Figure 4. The eye of a cuttlefish. Source: Adobe Stock]]~~

	To test the theory that their unique W-shaped pupil produced chromatic aberrations, a custom aperture mask was created and resulting optical image generated with a gridline scene. In the case of a larger pupil size, clear vertical lines and slightly blurred horizontal lines are seen, as expected given its overall horizontal slit-like aspect ratio. Additionally, clear red colour fringing is seen in the vertical lines, supporting this theory that one purpose of their unique pupil shape is to produce chromatic aberrations on their cone mosaic.		To test the theory that their unique W-shaped pupil produced chromatic aberrations, a custom aperture mask was created and resulting optical image generated with a gridline scene. In the case of a larger pupil size, clear vertical lines and slightly blurred horizontal lines are seen, as expected given its overall horizontal slit-like aspect ratio. Additionally, clear red colour fringing is seen in the vertical lines, supporting this theory that one purpose of their unique pupil shape is to produce chromatic aberrations on their cone mosaic.

WLP-LY-RS: /* Aperture */

2024-12-13T15:58:40Z

Aperture

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	===Aperture===		===Aperture===
	The aperture represents the pupil shape and is modeled as a 201x201 matrix. In this matrix, ones indicate the regions where light can pass through (white), while zeros denote the areas where light is blocked (black).		The aperture represents the pupil shape and is modeled as a 201x201 matrix. In this matrix, ones indicate the regions where light can pass through (white), while zeros denote the areas where light is blocked (black).
	For the single-slit elliptical aperture, we can adjust both the size and the orientation of the ellipse (vertical or horizontal). For the multiple-slit aperture, we can modify the slit length, slit width, and the number of slits. For the w-shaped aperture, we intake the w-shape black and white image to generate the aperture matrix, and are able to change the size of it.		For the single-slit elliptical aperture, we can adjust both the size and the orientation of the ellipse (vertical or horizontal). For the multiple-slit aperture, we can modify the slit length, slit width, and the number of slits. For the w-shaped aperture, we intake the w-shape black and white image to generate the aperture matrix, and are able to change the size of it. In this case we make use of the wvfAperture function, modified slightly to allow non circularly-symmetric apertures in a new function wvfApertureNonCirc. We make use of the wavefront structure in the ISETCam code.

	===Point spread function and optical image===		===Point spread function and optical image===

WLP-LY-RS at 15:57, 13 December 2024

2024-12-13T15:57:56Z

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	Cuttlefish are an interesting case in the animal kingdom. They are famous for their colorful displays and ability to dynamically camouflage themselves, yet they are actually monochromats, effectively colorblind. One paper [10] suggests they make use of chromatic aberration to distinguish between colours using their single photoreceptor type (at the cost of requiring more processing power behind their visual system).		Cuttlefish are an interesting case in the animal kingdom. They are famous for their colorful displays and ability to dynamically camouflage themselves, yet they are actually monochromats, effectively colorblind. One paper [10] suggests they make use of chromatic aberration to distinguish between colours using their single photoreceptor type (at the cost of requiring more processing power behind their visual system).

	[[File: Cuttlefish eye.png\| ~~900px~~\|thumb\|~~center~~\|Figure 4. The eye of a cuttlefish. Source: Adobe Stock]]		[[File: Cuttlefish eye.png\| 200px\|thumb\|right\|Figure 4. The eye of a cuttlefish. Source: Adobe Stock]]

	To test the theory that their unique W-shaped pupil produced chromatic aberrations, a custom aperture mask was created and resulting optical image generated with a gridline scene. In the case of a larger pupil size, clear vertical lines and slightly blurred horizontal lines are seen, as expected given its overall horizontal slit-like aspect ratio. Additionally, clear red colour fringing is seen in the vertical lines, supporting this theory that one purpose of their unique pupil shape is to produce chromatic aberrations on their cone mosaic.		To test the theory that their unique W-shaped pupil produced chromatic aberrations, a custom aperture mask was created and resulting optical image generated with a gridline scene. In the case of a larger pupil size, clear vertical lines and slightly blurred horizontal lines are seen, as expected given its overall horizontal slit-like aspect ratio. Additionally, clear red colour fringing is seen in the vertical lines, supporting this theory that one purpose of their unique pupil shape is to produce chromatic aberrations on their cone mosaic.
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	Furthermore, in 3D the W/U shape has the effect of being a vertical slit when viewed from the front, and a horizontal slit from the side. Potentially this could help the cuttlefish as an ambush predator, whilst still being able to scan for threats in the periphery.		Furthermore, in 3D the W/U shape has the effect of being a vertical slit when viewed from the front, and a horizontal slit from the side. Potentially this could help the cuttlefish as an ambush predator, whilst still being able to scan for threats in the periphery.

	[[File: W-shape pupil figure.png\| ~~300px~~\|thumb\|center\|Figure 5. W-shape pupil PSF and optical image of a grid scene. Upper figure has a 453px major axis length; lower figure has a 350px major axis length.]]		[[File: W-shape pupil figure.png\| 900px\|thumb\|center\|Figure 5. W-shape pupil PSF and optical image of a grid scene. Upper figure has a 453px major axis length; lower figure has a 350px major axis length.]]

	===Multiple-slit pupil: Mantis Shrimp===		===Multiple-slit pupil: Mantis Shrimp===
	The mantis shrimp is a case in of an animal from the same biome with a completely opposing approach to colour vision. It has an incredibly complex visual system with up to 16 different photoreceptor types, and an eye split into 3 bands capable of detecting even UV and circularly polarized light. However it has limited brain processing power behind this visual system, unlike the cuttlefish.		The mantis shrimp is a case in of an animal from the same biome with a completely opposing approach to colour vision. It has an incredibly complex visual system with up to 16 different photoreceptor types, and an eye split into 3 bands capable of detecting even UV and circularly polarized light. However it has limited brain processing power behind this visual system, unlike the cuttlefish.

	[[File: Mantis Shrimp Eye.png\| ~~300px~~\|thumb\|center\|Figure 6. The eye of a mantis shrimp showing its distinct 3-band eye structure and psueudopupils. Credit: Roy L. Caldwell/University of California, Berkeley]]		[[File: Mantis Shrimp Eye.png\| 200px\|thumb\|center\|Figure 6. The eye of a mantis shrimp showing its distinct 3-band eye structure and psueudopupils. Credit: Roy L. Caldwell/University of California, Berkeley]]

	The midband of the mantis shrimp eye is the only portion with multiple photoreceptor types. One study [9] showed that although they have a huge resolution in terms of sampled wavelengths, they are only effectively able to distinguish colours up to 25nm apart in the visible light spectrum. In order to investigate whether chromatic aberration plays a part in their colour vision like the cuttlefish, the triple-slit pupil was simulated in the same way as above. Also, a triple parallel slit pupil was simulated out of academic interest, although no animal is known to us to have this pupil shape.		The midband of the mantis shrimp eye is the only portion with multiple photoreceptor types. One study [9] showed that although they have a huge resolution in terms of sampled wavelengths, they are only effectively able to distinguish colours up to 25nm apart in the visible light spectrum. In order to investigate whether chromatic aberration plays a part in their colour vision like the cuttlefish, the triple-slit pupil was simulated in the same way as above. Also, a triple parallel slit pupil was simulated out of academic interest, although no animal is known to us to have this pupil shape.