Signing a document with an image in Ubuntu 12.10


Tired of printing a PDF, signing it and then scanning it back in as a PDF? Besides needing to use a printer/scanner twice, this also turns your entire signed PDF into an image, losing all of the textual information. This makes it impossible to do text searches on it later.

Here is a recipe to maintain that information and save some work for your printer/scanner.

One-time set-up

  1. Find a clean white piece of printer paper.
  2. Using a ruler, take a black pen and draw a small line where your written signature will go. Keep the line parallel to the top and bottom edges of the paper.
  3. Write your hand-written signature above the line (with the same black pen) as you would on a normal document.
  4. Scan this image with your scanner using Simple Scan. Save it.
  5. Open the image with GIMP (assuming that you already have it installed).
  6. Navigate to Layer -> Transparency -> Add Alpha Channel.
  7. Select the Fuzzy Select Tool from the toolbox.
  8. Click on each of the white areas around your signature that you wish to make transparent. Hit the Delete key after each one. This should be done for all areas except for the inked part where you signed.
  9. Navigate to File -> Export.
  10. Save the file as a PNG.

Signing each document

  1. Open the PDF you wish to sign with LibreOffice Draw. If it doesn't get imported properly, you may not have libreoffice-pdfimport installed. Make sure that it is.
  2. Navigate to Insert -> Picture -> From File... and select your PNG signature.
  3. Right-click on it and select Position and Size...
  4. Check the "Keep ratio" checkbox, and reduce the dimensions down to the preferred size.
  5. Move the line in the image over top of the signature line in the document.
  6. File -> Export as PDF -> Export.
  7. Enter the file information to save, and hit the Export button.
  8. Your new PDF file will contain all of the information as your old one, but your hand-written signature will now be attached.


signing with webcam

If you're not near a scanner, but have access to a webcam, or one's built-in to your laptop, then you can use the Ubuntu app Cheese Webcam Booth by holding up a scrap of paper to the camera.

You can get cheese from the Ubuntu Software Center.

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