Wallpaper resolution is 960 x 800. I'm not sure what you mean by "how to set a wallpaper without cropping the photo". If your talking about a black border or something to fill up the rest. You can try a live wallpaper called "MultiPicture Live Wallpaper" (Free) and there is a setting where there will be like a mirror effect on the top and bottom. However, I don't think you can span the wallpaper across the entire desktop. You have the choice to either have the same or different pictures on each of the 7 individual screens, you can also have the pictures shuffle like a digital picture frame from your sd card. But if you re-size the picture to 960 x 800 it fits perfectly. Hope this helps