Operating system: Windows 10 64 bit
Graphics card: Nvidia GTX 750 Ti
**Short description of error**
Reference Images have the wrong aspect ratio, if the //Limit Size// in the user preferences is set lower than the longest side of the image.
**Exact steps for others to reproduce the error**
Set the //Limit Size// in the user preferences, under Viewport > Textures to a value greater or less than 1024.
With values greater or equal to 1024, the reference image is rectangular.
With values less than 1024 the image becomes square.
**Optionally, file working in Blender 2.79**