Desktop wallpaper pictures too big for screen size

[Qslice]

I have just purchased a Toshiba Satellite L850 with Windows 8, and set the desktop wallpaper to a picture slideshow, but all of the pictures are far too large for the screen. The recommended resolution is 1366x768, which is what it is on, and is the highest it can go. Going lower just makes it worse. Same thing happens if I save a picture from the internet. i have hundreds of pictures and do not want to edit them all to fit, nor would I like to set it to 'stretch'. Can anyone help?

 

[Dharamvir]

Right click on empty space on your desktop and select the last option Personalise.
here select Desktop Background just above the taskbar.
on the lower left corner set the Picture Position to Fit from drop down menu.
Save the changes and you are done.

 

[ldoz]

Open the picture with Windows Photo Viewer. Right click on the image and select the option "set as desktop background", this will by default set the wallpaper to fit the screen.

 

[carolgwahl]

Dharamvir had given the solution. I think it works.