1.5 Photocapacitors as pixels
Perhaps you can also imagine an image-capturing array made up of MOS photocapacitor pixels. It's well within the scope of microelectronics to fabricate such an array of virtually identical, isolated MOS structures that would translate the pattern of light intensity falling on it into a pattern of charge. There's more to it than that, though, because:
each capacitor must be simultaneously connected to a power supply that provides the reverse bias
to transfer the information into a stored image requires the read-out of the charge at each pixel.
Working out how to meet these challenges requires a clear target in terms of performance specification.