The issue was the strange format alpine have their wallpaper images in. A guy figured out how to decode the pictures and managed to find way a to convert normally pictures to alpine format. He had his own website "http://www.pride-rock.com/forum" and changed picture formats for people and stuck them on his website for them to download. His site has recently been shut down.
If your after a custom picture like "boobs" your onto plumbs I think.
However I know of car ice install company who has a list of manufacture logos in alpine format saved on a CD. If you can get a hold of them they might be able to send you the nissan logo. They are Austrian, "Northfield moorooka" you can find them on Facebook and online. Send them a message and they might be able to hook you up.