ExtractFoxHow to extract a signature from a PDF or an image
Whether you need to verify a signature exists, lift it as a transparent PNG for reuse, or pull every signed name as text — here are the right tools for each version of the question.
"Extract a signature" usually means one of three things. The right approach depends on which one you need.
1. Verify a digital signature on a PDF
If the PDF was signed with a certificate (Adobe Sign, DocuSign, government eIDAS), open it in Acrobat Reader and check the signature panel — it'll tell you who signed, when, and whether the certificate is valid. For a programmatic check, pyHanko (Python) reads and validates PAdES signatures and returns signer details and timestamp.
2. Lift a handwritten signature as a transparent PNG
Common need: you have a scanned document with your own signature on it and want to reuse the signature image elsewhere.
- Crop to just the signature area in any image editor.
- Open in GIMP or Photoshop. Use Select by Color (or Color Range) to select the white background.
- Invert the selection, copy to a new layer with transparency, export as PNG.
The remove.bg API does this automatically if you don't want to fiddle in an editor.
3. Identify who signed and pull the printed names
Signature blocks usually pair the handwritten mark with a printed name and date. For audit or tracking purposes, the printed text is what you actually want.
ExtractFox's contract extractor handles this through the standard contract schema: signer name, signed date, role, organization. For ad-hoc signed documents that aren't contracts, the free-text mode with a prompt like "extract every signature block as a row with printed name, role, and date" works well.
What you can't reliably do
Match a handwritten signature against a known sample to verify identity. That's a forensic discipline, not a software feature — academic papers exist, commercial tools claim it, results in real disputes need a human expert. Don't build authentication on automated signature comparison.