Summary: @public
It's less important to reload for downscaling than upscaling, so increase the threshold in that direction. Also, this now considers each dimension separately, and a big enough change either way should result in a reload.
Finally, this considers both the current image size and the inflight target size, so we don't reload if either is already good.
Reviewed By: @tadeuzagallo
Differential Revision: D2470911
bcd2ef5dfc