Sharp sprites when blur after resize[discussion]

[YinYin]

Resizing always requires some interpolation and there are many different methods for that.
You need to find out whether you can switch to a sharper interpolation method in paint.net - just go through the settings.

I like using a normal bicubic one. If you don't want any blur you can try "nearest neighbour".
Usually there is also "bilinear" and "bicubic sharper"/"bicubic smoother". Just try whatever you can choose.