setting opacity of background image in css code example

Example 1: css opacity example

.opacity30 {
  opacity: 0.3;
  filter: alpha(opacity=30); /* For IE8 and earlier */
}

Example 2: transparent background css for image

background-color: rgba(255, 0, 0, 0.5);

Example 3: image opacity in html

img {
  opacity: 0.5;
}