'Pixel Binning' In Improving Smartphone Photography, With One Big Disadvantage

There was a time when cameras on mobile devices were less than 1 itty-bitty megapixel. But fast-forward, people have smartphones with multiple cameras, each with huge megapixels.

A megapixel consists of one million pixels (picture element), The unit has been used for image sensing capacity in digital cameras. In general, the more megapixels a digital camera has, the better the resolution when printing an image in a given size.

With more and more megapixels packed into a camera sensor, what more can companies do to further improve the quality of pictures?