How can you sharpen the self-inserted images in the paintings (Minecraft)?

I found out how to add pictures to paintings in Minecraft a week ago, when I added all the pictures I wanted now it worked, but no matter which picture I was on, it was either just slightly pixelated or almost even completely pixelated.

Now I've already tried to insert 4k images to see if the graphics change, but unfortunately it wasn't, which also means that my images don't have too few pixels. But yesterday I discovered a texture pack in which the paintings are as good as not pixelated at all, so I wanted to ask how Minecraft makes the images in the painting sharper

So if you look in the txt pack then there's somewhere (you should find it pretty quickly) a file which somehow means "maps" or something. If you open this with Paint.NET then press Ctrl + R you enter as new size e.g. 4096 then your map file is 4k in size and you can import 4k images!

For me there's only something that says clipboard

I'm sorry… I used the wrong paint, but to be precise, I can't really find maps or anything