This is nothing more than a resized image from Microsoft's Xbox website. Dimensions are 1920x1080.
I take no credit in creating any of the images and/or scenes depicted in "Halo 4 Wallpaper." All images are licensed and copyrighted by their respective creators.
"Halo 4 Wallpaper" was created under Microsoft’s “Game Content Usage Rules” using assets from Halo 4, © Microsoft Corporation.