Apple - Extract an image file of my signature from Preview?

You can alternatively try to insert your signature in a blank pdf document, crop to take only your signature and then save the document as a PNG file.

FYI, it's seems that the signature is stored in a .plist file. The file name is "com.apple.Preview.signatures.plist" and it's in folder : /Users/YourAccount/Library/Containers/com.apple.Preview/Data/Library/Preferences/

Hope this helps !

It appears that Preview stores the signature files in an undocumented, encrypted form directly in the Keychain. Without hacking their encryption and storage format, the file cannot be extracted...

but if you can make the signature appear on screen, you can capture a screen shot of said signature, and use that file in another application.

this solution worked for me using 10.8.2 (mountain lion)

http://www.stuartcarnie.com/2011/08/transferring-preview-app-signatures-in.html