NPOT texture problem

I am making a small paint program and am using read pixels to do a screenshot to bake the image.
The problem I am running into on iOS is that the NPOT texture wont display.

I am thinking of using a POT but seems like a waste of memory because the top and bottom pixels wont be used.

I would rather use a screenshot that is the device aspect ratio. but that wont be POT.

is this doable?