Extract an image file of my signature from Preview? The Preview application in OS X Lion includes the ability to take a screen capture of your written signature and save it for later application in to any PDF file.

Where does Preview store the image file for this signature? Is it possible to extract the signature for use in another application like Adobe Reader?
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 !