Can I set background image and opacity in the same property?

Question

I can see in CSS references how to set image transparency and how to set a background image. But how can I combine these two in order to set a transparent background image?<

Answer 1

Two methods:

1. Convert to PNG and make the original image 0.2 opacity
2. (Better method) have a
   that is position: absolute; before #main and the same height as #main, then apply the background-image and opacity: 0.2; filter: alpha(opacity=20);.