Perhaps not general shots on Instagram, but a larger face picture might have a 80x80 pixel area on one eye. Not enough for a real iris scan maybe, but quite possibly enough to identity an individual?
And as high-DPI screens get more common, ordinary snapshots online will probably move up from the low resolutions they are now.
And as high-DPI screens get more common, ordinary snapshots online will probably move up from the low resolutions they are now.