Need Help wit icons for the PM 3.5 Stage Select

[Juken]

I'm trying to add back a few of the stages from my old PM custom build into 3.5, but I noticed that every stage has a set icon size of 64 x 56. for the large iSSS icon. My old custom build had icons that varied from a number of sizes and now I want to resize them to be smaller for a more consistent organization. There's two issues I've noticed though. The first one is that when I resize them in photoshop, they become become very low quality, and when I put them into the Stage manager or brawl box, they become very low blurry looking and low quality. This bothers me because the new stage select screen has those icons expanded to be very large, and I don't want them looking like a low quality mess.

Does anybody have any advice for how to resize my old icons to be 64 x 56 without ruining the quality? I currently just resize them in photoshop by dragging them onto a 64 x 56 canvas and resizing them with cntrl+t. Here's some of the old icons before I tried resizing.

Or could I just stick these much larger images into my game without resizing them while avoiding a crash?