Red-eye is induced by the flash and was never part of the reality being captured.

1. Engineering constraint: the camera is not as sensitive to light as humans

2. Workaround: it emits a flash which creates an undesirable side effect

3. Fix: we clean up in software

Is like?

1. Engineering constraint: The camera can't be positioned behind the LCD panel the user is actually looking at

2. Workaround: it's placed 1 inch above which creates an undesirable side effect

3. Fix: we clean it up in software

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In both cases we get closer to where we'd be if the engineering constraint did not exist.