RECOMMENDED: Click here to fix Windows errors and optimize system performance
Windows 8 users have a limited number of images from which they can select and set an image as the startup wallpaper. There has always been a desire among Windows 8 users to be able to set their wallpaper as their startup wallpaper. Under Windows 8.1, Microsoft has introduced this customization feature, which allows users to automatically set their desktop background as the startup screen background. There are two ways to change this setting.
Show the desktop background as the startup screen background
About the startup screen customization settings
Go to your Windows 8.1 startup screen and open the Charms bar. Click Settings, and then click Customize. You will see the following options in the charm bar itself.
You can now choose from 14 backgrounds, set your desktop background as a background, or set background and accent colors.
Right-click the Windows 8.1 taskbar and select Properties. This opens the Taskbar Properties field. Under the Navigation tab, you see the option Show My Desktop Background at Start. Check, click Apply/OK and Exit.
However, you cannot set an image as the background for the start screen, as you can for your lock screen.