How can I remove the unwanted background from a scanned handwritten signature?

Question

I need to upload my signature in a PDF document, but I do not know how to edit the background of this image.

I wish to remove the bluish-tint background, and make it pure white.

Can anyone help me with this, please?

Answer 1

If you have access to Photoshop, try the Magic Wand tool to select the background around the writing, and fiddle with the Tolerance to get it as close to the writing as possible, then delete or fill with white.

Another method is to use Image > Adjustments >

Selective Colour - With Selective Colour you can tweak the thresholds of each colour, so in your case I'd probably reduce magenta a little.

or

Replace Colour - With Replace Colour, you can select the blue you want to lose and replace with white, though you may have try a few times as it might target some of the blues in the signature as well.

The easiest and fastest method for a non-designer with access to Photoshop would be like this:

1. Open the file in Photoshop. (CS5 in screenshots)
2. Select the Magic Wand tool on the tool bar, on the left of my screen but may different for you.
   • Make sure you haven't got the Contiguous checkbox at the top selected.

3. Click on the background, see how much of the background is selected, adjust Tolerance, in this case I found 20 to be satisfactory for a quick demo.

4. Press Delete

5. Add a solid color layer, select white when the color picker pops up.

6. Move the solid color layer to be behind the signature layer

7. Et Voila, save in the format you need it

With a little more effort, you could make a much better finish.

There are many other methods to achieve this, as it's a very simple task with the right tools.

Answer 2

Let me outline another approach I find useful especially in the context of a signature for letters or PDF documents.

We can quite easily create a vector graphic from a scanned original signature. This can be done with a variety of applications. Here is how I made it using Inkscape.

1. Import the bitmap into an empty document (select "embed").
2. Select the "Path - Trace Bitmap..." tool.

3. Trace the bitmap with the following options:

   • Colors: 4 to 8 (more gives finer details)
   • Select: Smooth, Remove Background
   • Adjust the Options to your needs (defaults will give reasonable results)

4. Choose the "Path -Simplify" tool for a smaller file size.

5. Save the resulting .svg vector graphics:

   ^{Paste of the 56kB .svg here: http://pastebin.com/6ncTamRB}

We can then further refine the resulting colours, or apply variable transparency levels to the objects created if we need better results.

A vectorized signature has the advantage that it can be smoothly resized to any size, can be differently coloured with no effort, and it can be embedded in a variety of documents as a rather slim vector graphics.

Answer 3

There are lots of methods to achieve what you want in Photoshop.

You can use a non-destructive method such as a layered Gradient Map.

1. Simply create a new adjustment layer from Layer > New Adjustment Layer > Gradient Map...

2. Choose the Black to White Gradient and adjust the gradient stops accordingly.

3. Make sure that the adjustment layer is on top of the signature.

Take note that the signature isn't cut out from its background. If you want a transparent background, simply flatten all layers and use the Magic Wand. The selection will be more accurate with lesser tolerance adjustments since the image now has a higher contrast.

Answer 4

This is very easy in Gimp. Just use the bucket tool to fill the background white, and export. Or if you want to go one stage further, then after that, use the select with the same colour tool, press delete (Making sure that your image has an alpha channel) add a new white layer, merge down and export as a jpg, png or whatever.

Answer 5

Using Photoshop, this is the best way I know to get rid of a background while preserving the integrity of something that has been sketched or drawn and you will get much, much better results than using the magic wand

1. Select all of your image and copy it in a new channel (the channel created should be named "alpha" automatically)

2. In the channel, Ctrl+click or cmd+click on the thumbnail to create a selection

3. Go back in your layers and create a mask while the selection is still on,then invert it using ctrl+i or cmd+i

4. Delete the previously made alpha channels

5. You can clean up the mask or use refine mask if needed

6. Use a solid color layer with it, if you easily want to change the color.