Working with DNGs in Lightroom gives you the ability to install an useful plugin to recover real image size as captured by the camera sensor.
When you have a good image with some cropped pixels on one edge, you could probably recover them with this plugin:
DNG Recover Edges
The plugin will work with any camera:
The RX100 recovers 248.832 pixels, from 5472x3648 to 5504x3672 pixels.
The A900 recovers 226.304 pixels, from 6048x4032 to 6080x4048 pixels.
The A99 recovers 272.768 pixels, from 6000x4000 to 6032x4024 pixels.