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How to make an electronic signature

December 29, 2010 4 comments

It’s often useful to add your signature to a Word document instead of manually signing the actual paper with one of those pen thingies. Of course, the easiest method is to just sign a piece of paper, scan it, and insert it as an image. It’s simple to do, but because the scanned image is a bitmap it often looks rubbishy and pixellated when you print it or save it as a PDF.

The solution is to create a vector signature that is guaranteed to look fantastic at every scale. There are lots of methods out there. Here’s mine – it uses free software and is quick to do.

1. Sign a piece of white unlined paper. Choose your best, most representative signature, and scan it (400 dpi or so is usually good enough). Here I’m using the signature of a famous personage that I found online, rather than my own embarrassing scrawl.

Colour signature

2. Change the image to grayscale, and adjust the levels – Auto Levels usually does the trick. You can use Photoshop if you have it, but I use GIMP (GNU Image Manipulation Program), which is free and awesome. Get it from www.gimp.org/downloads. Save the signature as a JPG at high quality (95 or so). It should now look more like this:

B&W signature

3.  Open in the file Inkscape (the open source SVG graphics editor). You can download it from inkscape.org/download – it’s also free and awesome.

Signature in Inkscape

4. Resize the page to fit your signature (File menu -> Document Properties -> Fit page to selection):

Document properties -> Fit page to selection

5. Create a vector version of the signature by using the Trace Bitmap function from the Path menu. You can play around with the settings to fine-tune things, but I find I get good results using a single scan, the brightness cutoff method, thresholds at 0.880 and 0.970, and a 2 colour output. Press OK.

Trace the bitmap

6. Your vector image is now sitting on top of your bitmap image, which you no longer need. Delete it by selecting it, moving it to the side, and pressing the delete key.

Delete the bitmap

7. Resize the page to fit your new vector signature (File menu -> Document Properties -> Fit page to selection).

Fit to selection again

8. Now save it! From the File menu, choose -> Save As -> Enhanced Metafile (.emf).  There are lots of different vector filetypes you can use (.svg for example), but .emf is a good format for inserting into Word.

Then just insert your signature into Word as a picture, making sure the scale is appropriate (this might involve printing it out a few times to check). Make the image sit “in front of text” if you want to allow it to slightly overlie the typed text.

So that’s it! The result looks very professional, prints really well (it looks jet black on a laser printer!), and withstands infinite zooming when it’s in a PDF:

Comparison between the bitmap and vector images

Enjoy!

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