Use pictures from Modern-Bing app on Windows 8 lock screen
The app instantly change the lock screen to the current image.
If you want to save these photos for other purposes (e.g., for use on a smartphone), press the keyboard Win + R, in the text field of the dialog box «Run» type the command %userprofile%AppDataLocalPackagesMicrosoft.Bing_8wekyb3d8bbweLocalState and press Enter.
You will open the folder where you will find all the pictures that were used on the lock screen.
Each photo is available in landscape and portrait options, the latest you can use on your smartphone.