It's mindblowing simple but very effective. Only a couple of steps, but the outcome is in my opinion very nice.
Step 1:
Open a blank canvas of whatever size you wish your sig to be. I went with 400 x 150.
Step 2:
Paste in whatever picture you want to use in your sig, and resize it so it's the same width as your sig, and move it to where you want it. Make sure it's the only layer you have by deleting any others that show up in your layers box. This is what I have so far:
Step 3:
Duplicate your layer with Ctrl + Shift + D.
Step 4:
Desaturate the bottom layer, which was the original. On Photoshop, this I think is Ctrl + Shift + U. On GIMP, simply go to the Colours drop down menu and click Desaturate, select 'Lightness' and click OK.
Step 5:
On the top layer, change the mode to "Soft Light". Hard light also works, but I'd recommend Soft Light.
Step 6:
Simply add a 1 pixel x 1 pixel black border, and you're done.
So there you have it. A good looking signature, and you hardly had to do anything complicated.
