Originally Posted by
blue1k No I meant they should advertise the effective size. I understand the physics.
My SLR is advertised at the effective output of the image as are other cameras.
A) No smartphone OEM does this. Everyone advertises sensor resolution. Advertising the lower MP number in the interest of "honesty" would be akin to one OEM deliberately putting themselves at a marketing disadvantage.
B) Many camera sensors are rectangular, not round, so in those situations advertised sensor resolution = image resolution (edit: provided sensor aspect ratio = image aspect ratio).
C) Even if an OEM using a round sensor wanted to be more "honest", which of the many aspect ratios should they choose? As with all specs, this is an oversimplification, but in this particular instance it may not be the worst choice.