Windows 8.1 now includes the ability to stream an image slideshow when your PC is locked. Find out how to apply it to your user session in less than 5 minutes.
To do this, in mode Modern UI (touch interface), move the mouse cursor to the top right corner of the screen and descend down to access the charm bar.
Click on the link Modify PC settings located downstairs.
Click on the 1st link entitled PCs and Peripherals.
Under Lock Screen, in the part Slideshow, check the box Read a slideshow on the lock screen.
You can also check the box Read a slideshow in case of battery operation.
Then click on Add Folder to select the folder of the images that will be used in the slideshow.
The changes are immediate. Make Windows + L to admire the result.
A nice option to turn your tablet into a digital photo frame when it is unused.