In Windows 10, when viewing an image with explorer you can right mouse click on it and then select set as background to make an image your desktop background or wallpaper.
Set your desktop background color to black - right mouse click on an open area in your desktop, select properties and then desktop. Copy the images you want for your screen saver or wallpaper to a directory on your disk drive from the uvminerals/images directory. Then configure the screen saver or automatic wallpaper changer to use the new images.
Photographic Images © 2003 James O. Hamblen