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

I have used the answer of @Dan Eastwell and it works very well. The code is similar to his code but with some additions.

.granddata {
    position: relative;
    margin-left :0.5%;
    margin-right :0.5%;
}
.granddata:after {
    content : "";
    display: block;
    position: absolute;
    top: 0;
    left: 0;
    background-image: url("/Images/blabla.jpg");
    width: 100%;
    height: 100%;
    opacity: 0.2;
    z-index: -1;
    background-repeat: no-repeat;
    background-position: center;
    background-attachment:fixed;
}