Human Eyes as Digital Cameras?

Mad Dog Kenrod asks: "A recent ad campaign for a digital camera had the slogan (something like) 'imagine being able to take a picture from your head and show it to people' - it was basically showcasing how small the camera was. This got me thinking: most people simply want to 'snap what they see'. Given that the human eye already has a very workable lens, and a retina which (I assume) is similar in technology to a digital camera, how feasible would it be to 'tap into' the optic nerve (not the brain, because by then the 'image' is probably something else entirely) and turn the signals from all those rods and cones into pixels?"

"Given we can do C.A.T. scans, would it even be feasible to do this from outside the head (say, with sufficient miniaturization, from the arm of your glasses)?

Of course, you would lack other things like zooms and filters and even an ability to 'frame' the picture (and there'd be problems for people with eye disease), but I propose that, for the majority of us who just want to quickly 'snap what we see' this would make for the smallest, lightest camera possible.

I know nothing about what would be involved in making this happen, so would be interested in people's thoughts."

Perception

[xyzzy]

The problem is that you'd probably get a *shitty* picture. Or at best, it wouldn't reproduce "what you saw" any more than a regular camera does.

The majority of what you "see" is exactly because of the post-processing your brain does, as well as your eye and optic nerve. This occurs both in the optic realm (shading, motion, etc), and because your brain applies all kinds of cognitive processes to the visual signal. It isn't simply a passive sensor like a CCD.

Re:Nearly Impossible

[MacJedi]

The problem is that if you tap in at that point (and let's pretend that you could sink enough electrodes into the retina; if you're tapping in at that level you'd have to hit a significant percentage of them) the raw image would be very poor. You'd have to do all the processing yourself, in hardware and the required processing is not fully understood.

I'd suggest that you'd be better off letting the brain do most of the processing and take output from the visual cortex. I believe there has been some success doing this with blind persons. Tapping into the optic nerve is a tempting compromise, but remember that the optic nerve is made up of hundreds of axons. I doubt a simple cuff electrode would do the trick-- you'd need to get the firing rates for each one (or at least some large percentage of the axons) and this is beyond the current state-of-the-art, afaik.

In any rate, cat example you're citing was for tapping into the thalamus. That's about smack dab in the middle of the brain. Some of the computation is done and some isn't, so that might be a good compromise.

It's important to realize that there is computation done at virtually every step of the path from retina to the visual cortex. There is no passive transmission of data (afaik) so each part is important.

/joeyo