Convert image

[EMcCulloch]

This is my first panorama with this software.

My input file is a cylindrical tiff/jpg of a 3d model (room) rendered with 3Ds MAX.
Is there an advantage from converting the input file to any of the "cube" form? Do you loose image quality while doing it? I could lower the file size since I don't need high quality of the floor and ceiling, but is there any other reason the input file could/should be converted?

Thank you.