The VG Resource

I tried to submit these sprites, but they were rejected.  they said it's because it 'does not have a 1:1 pixel ratio.'  How do I fix that?

A 1:1 pixel ratio is it being at a size where detail doesn't look to have been omitted, and can be properly resized into cardinal multiples (2x, 3x).

Unfortunately, with the attachment provided, and the transparency issue involved when I copy it into a editing program, there's little for me to work with to suggest, since the sprite's outline merges with the black backdrop, and the entire thing is a JPEG that makes detail impossible to read.