The files are JPEG images with unique names.
Now, we just need to make sense out of this mess of data that you just found. Here’s how to identify the right wallpaper files. These are typically the images with the largest file sizes. If you’re planning to use any of the Windows Spotlight images on your desktop PC or laptop, you’ll want the desktop-sized versions of these images. These files are your Windows Spotlight lock screen images, listed in a variety of sizes and formats.