Set opacity of background image without affecting

Question

Is it possible to set the opacity of a background image without affecting the opacity of child elements?

Example

All links in the footer need a custom bullet (background image) and the opacity of the custom bullet should be 50%.

HTML

<div id="footer">
    <ul>
        <li><a href="#">Link 1</a></li>
        <li><a href="#">Link 2</a></li>
        <li><a href="#">Link 3</a></li>
        <li><a href="#">Link 4</a></li>
        <li><a href="#">Link 5</a></li>
    </ul>
</div>  

CSS

#footer ul li {
    background: url(/images/arrow.png) no-repeat 0 50%;
}  

What I've Tried

I tried setting the opacity of the list items to 50%, but then the opacity of the link text is also 50% - and there doesn't seem to be a way to reset the opacity of child elements:

#footer ul li {
    background: url(/images/arrow.png) no-repeat 0 50%;
    /* will also set the opacity of the link text */        
    opacity: 0.5;
}

I also tried using rgba, but that doesn't have any effect on the background image:

#footer ul li {
    /* rgba doesn't apply to the background image */
    background: rgba(255, 255, 255, 0.5) url(/images/arrow.png) no-repeat 0 50%;
}

Answer 1

The "filter" property, needs an integer for percentage of opacity instead of double, in order to work for IE7/8.

filter: progid:DXImageTransform.Microsoft.Alpha(opacity=50);

P.S.: I post this as an answer, since SO, needs at least 6 changed characters for an edit.

Answer 2

#footer ul li {
  position: relative;
  opacity: 0.99;
}

#footer ul li::before {
  content: "";
  position: absolute;
  width: 100%;
  height: 100%;
  z-index: -1;
  background: url(/images/arrow.png) no-repeat 0 50%;
  opacity: 0.5;
}

Hack with opacity .99 (less than 1) creates z-index context so you can not worry about global z-index values. (Try to remove it and see what happens in the next demo where parent wrapper has positive z-index.)
If your element already has z-index, then you don't need this hack.

Demo of this technique.

Answer 3

You can put the image in the div:after or div:before and set the opacity on that "virtual div"

div:after {
  background: url(https://s3-us-west-2.amazonaws.com/s.cdpn.io/3/owl1.jpg);
  opacity: 0.25;
}

found here http://css-tricks.com/snippets/css/transparent-background-images/

Answer 4

Another option is CSS Tricks approach of inserting a pseudo element the exact size of the original element right behind it to fake the opaque background effect that we're looking for. Sometimes you will need to set a height for the pseudo element.

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;   
}

Answer 5

You can use CSS linear-gradient() with rgba().

div {
  width: 300px;
  height: 200px;
  background: linear-gradient(rgba(255,255,255,.5), rgba(255,255,255,.5)), url("https://i.imgur.com/xnh5x47.jpg");
}
span {
  background: black;
  color: white;
}

<div><span>Hello world.</span></div>

Answer 6

This will work with every browser

div {
 -khtml-opacity:.50; 
 -moz-opacity:.50; 
 -ms-filter:"alpha(opacity=50)";
  filter:alpha(opacity=50);
  filter: progid:DXImageTransform.Microsoft.Alpha(opacity=0.5);
  opacity:.50; 
}

If you don't want transparency to affect the entire container and its children, check this workaround. You must have an absolutely positioned child with a relatively positioned parent.

Check demo at http://www.impressivewebs.com/css-opacity-that-doesnt-affect-child-elements/