how to set opacity to background image

#bg{
background-image: url('images/wood1.jpg');
opacity:0.2;
width:300px;
height:300px;
}

/*
  You have to fake it, as there is no such property
*/

div {
  width: 200px;  /* Image Width */
  height: 200px; /* Image Height */
  display: block;
  position: relative;
}

div::after {
  content: "";
  background: url(image.jpg);
  opacity: 0.5;
  top: 0;
  left: 0;
  bottom: 0;
  right: 0;
  position: absolute;
  z-index: -1;   
}

The following example sets the opacity for the background color and not the text: 100% opacity. 60% opacity. 30% opacity. 10% opacity. You learned from our ...

img {
  opacity: 0.5;
}