background image opacity with background color code example

Example 1: Background image opacity CSS

div {
    opacity : 50%;
}

/* Use opacity to change the opacity of selected css */

Example 2: set background image with color with opecity css

div {
  width: 200px;
  height: 200px;
  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;   
}