Input image size

[Liquidmasl]

Hey community,

I fail to find information about the image input size, I see images are transformed into 800 times 800-1300 or something similar, why were this resolution chosen?
I work with images that are 4000x8000 so I will probably have to tile them, but could i use other input sized as well? or does it need to stay close to that so it even works?

Thanks for any input (: