How do I get old wallpapers back from ios 6?

Hi,

I recently updated my iPad to iOS 7, and I had my homesreen with an ios 6 wallpaper picture. I was looking around with the wallpapers when I accidently put another wallpaper. I wanted to change it back, but I saw that wallpaper is not there anymore! I saw some of the other ios 6 wallpapers, but not the one I had. Mine looked like this:

I also tried to save this picture to my camera roll to set it, but it won't fit on the screen. I am really frusturated with this. Please help. 😢