Yeah, what @apparently_weird said.
If you aren’t familiar with the terms raster/vector,
Raster images are composed of square pixels. If you zoom in on a “line” in a photoshop image, what you’ll find is something like graph paper with individual squares filled in varying shades of color.
Vector images are essentially comprised of mathematical formulas.
As such, a vector curve will be much smoother than a rastered curve.
If the only file you have is a photoshop file, open it in Illustrator and use the Auto Trace feature to get true vector outlines of your image.
Warning: This may require a LOT of cleanup work to get smooth lines… Sometimes, I’ve found it faster to lock the photoshop import in one layer, and manually trace the line(s) for the image.