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Lecture 19: Introduction to Color Science (25)

Actually octopus has advanced eyes structure than human. Their photoreceptor cells are in front of the retina, unlike human. This avoid the presence of the blind spot, where human eyes' photoreceptor cells need to provide the space in blind spot for optic nerves to go through.


Prof Ren mentioned in class that the focal length is roughly 17mm in the human eye -- but there must be differences in everyone's eyes. I wonder if some people are born with eyes that are sort of more "sharp" to colors and perception than others. One way I thought about it is that some people are born with eyes that are "less sharp" (e.g. think colorblindness) - in that sense, I guess the answer to my question is yes? Would love to see how others think about this problem.


To chenwnicole: I found this information regarding sex-related differences in color vision:

"Factors that might influence color vision [include] variation in macular pigment density, lens pigment density, the position of the cone spectral sensitivity (i.e., cone polymorphism), cone-pigment density, as well as rod intrusion."


If the focal length is roughly 17mm in the human eye (as a prev comment states Ren stated in class), why is it commonly said that a 50mm focal length camera is the most similar to what the human eye sees?


It's mentioned in lecture that "most of the refractive work is handled by the cornea," so it acts like an outermost "camera lens" of sorts that helps focus light coming into the eye. Additionally, the cornea is also helps to filter out some of the most damaging UV rays in sunlight, helping to protect the eye from UV radiation. More information:


it is hard to imagine that in reality, we are all receiving different colors. Due to different physical features, different screens we have and etc


In response to the 50mm focal length camera question, the answer is related to the fact that the focal length of the eye doesn't determine its angle of view. In reality, the eye's cone of visual attention is about 55 degrees wide, which corresponds to a 43mm lens on a 35mm full frame camera. More information can be found at this link. Long story short, the eye is not quite the same as a camera.

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