[Feature Request] - Higher dimensions please?

[Hamtaro19]

I've got some images that I'd like to add as BGs, but they're too big apparently. They're likely too large but more or less around 6456 x 3764 as a landscape, and 5400 x 7400 as a portrait. If it cannot be done, could you at least allow us to resize or choose between fill, fit in, centered, covered, contained for both landscape and portrait images? Thnx :)