Yep, it just uses ImageMagick's `convert` to take the PDF, rotate it a little bit, blur the text, and generally reduce the quality just like a scan would.

The OP also uses a few other flags like `+noise Gaussian` and `-attenuate 0.25` which you could toss in. Same concept, just wanted to share a one-liner you can use if you already have a PDF with a signature on it, and you need that nice "scanned" look.