The Eye

John K Clark (
Thu, 22 Jan 1998 10:12:36 -0800 (PST)


On Thu, 22 Jan 1998 Charlie Stross <> Wrote:

>The human eye contains, in effect, two different imaging systems:
>the fovea, and the rest of the retina.


>The rest of the retina combined has about the same number of
>photoreceptive cells, and covers a much wider field; it's less
>sensitive to colour, much lower resolution, but is functional in
>very low light levels.

Light sensitivity is irrelevant, we're talking about the amount of information
that the brain gets from an eye in normal operating conditions. Peripheral
vision is good for spotting motion, but it doesn't take much information to
alert the brain of something of interest so it can turn the eye and the fovea
can get a good look at it.

>I think there are some figures for visual data sensitivity in Foley,
>Van Damm et al, but it's a while since I had to read that (read:
>since I last had anything to do with real-time photorealistic
>rendering for simulator graphics engines). About 4kx4k pixels
>springs to mind ...

That would mean we could distinguish between 16 million objects without
moving our eye at all! The letter "l" in "resolution" just does not seem to
me to be made of 16 million parts, something is not right. Even in the
unlikely event that the fovea was capable of such a prodigious feat, I doubt
it could transmit the description, and even if it could the brain is
certainly not able to handle such a glut of information.

John K Clark

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