How to make Backdrops (the easy, and the messy way)
So Blendartists wont host the images, due to the absurd aspect ratio, but ill host them on my g-Drive.
(Thats the basics)
After that its time to move to photoshop/gimp.
You may need to crop the image.
Then you need to remove all saturation and invert the image. Then mess around with the curves to get a pure black and white image.
Heres an example: