Sorry for the wait. I will try and work on a tutorial for everyone on the forums to look at with pictures of the process.
You'll need:
Paper or signature book (preferably w/white paper)
Thick Black Marker (kids scented felt could work too though I used a perm. marker and for best results I recommend it)
Flatbed scanner or All-in-One w/flatbed
Photo editing software (I will demonstrate with Photoshop later)
The easiest way to explain it is this:
We bought an autograph book down in
Disneyland, but we took a couple of thick permanent markers with us because I knew that I was going to do this. And when I say thick I don't mean a regular tipped sharpie. I mean something bigger than that, you need like a good width when they sign their name. I would say something that makes a good 1/4" wide stroke or so (I suggest a round tip too, chisel tips give mixed results).
Get all of your characters to sign with the felt, don't worry too much about bleed through as that can be corrected later. So long as each signature looks fluidic and smooth.
Once you get home, all you have to do is scan each signature into its own file, any type will do, jpg is fine, quality won't make too much of a diff.
For each signature you have to use photoshop to clear the white background so that the signature is sitting on a transparent background. Then you will open the photo you and the character and either place or copy and paste, however...to get the signature onto the photo. Move it into a good place. Now play with the blending options of the signature layer. If you aren't too familiar with photoshop don't worry, this part is a lot of trial and error and I will show some of my favourite options when I write the tutorial. As you can see from the pic I posted I used things like a gradient overlay a light drop shadow, and and outer glow. I framed a picture with Pluto because I loved what I did with it in Photoshop.
I posted this in another thread, but this one is actually from Disney World. I only did a few from our WDW trip in '09. Kinda got side tracked and never got back to extracting the signatures from the book. I did a few, so far this one and another I have with Chip and Dale are my favourites.