>>4085591Foveon does not have a filter array.
Wavelength is selectively absorbed based on penetration depth into the photodiode stack (selected by wavelength using layer thickness). In theory this means sensitivity should be increased over a bayer filter array as the only photon absorption is occurring in the photodiodes themselves, but in practice the diodes are not perfectly homogenous elements in the Z-axis, but the 'thickness' of the film that is actually active volume is lower than the total thickness of the stack. Since there needs to be insulators between each layer at an absolute minimum (and you need to stuff the transistors and wiring in there somewhere too) it's not trivial the increase capture efficiency.
Conversely, a bayer (or any other CFA filter sequence) array sensor filters out 2/3 of the photons before they even reach the diodes, but once they do the diode active layer thickness per pixel can be thicker than the entire Foveon diode stack.
