
Cover
The background image fits the screen
Top image fits to layout

Cover + Alpa Channel
Set opacity with Slider

Tile
the background image is tiled
keeping original size

Tile+ Alpa Channel
Set opacity with Slider

CSS filters with Slider
Body background image

Brightness
Contrast
Saturate
Invert
Grayscale
Sepia
Opacity

+ CSS filter
This further effect is available with fixed value
BLUR