CSS background-image-opacity?

Question

Related to How do I give text or an image a transparent background using CSS?, but slightly different.

I'd like to know if it's possible to change the alpha value of a background image, rather than just the colour. Obviously I can just save the image with different alpha values, but I'd like to be able to adjust the alpha dynamically.

So far the best I've got is:

<div style="position: relative;">
    <div style="position: absolute; left: 0px; right: 0px; top: 0px; bottom: 0px;
                      background-image: url(...); opacity: 0.5;"></div>
    <div style="position: relative; z-index: 1;">
        <!-- Rest of content here -->
    </div>
</div>

It works, but it's bulky and ugly, and messes things up in more complicated layouts.

What's behind the background image? A solid color, or another image? — Eric
– Eric, Commented Jul 31, 2011 at 15:57
@Eric: I'm not referring to any specific case with this, I'm trying to find a general solution to the problem. — Niet the Dark Absol
– Niet the Dark Absol, Commented Jul 31, 2011 at 16:38
@Kolink: I'm trying to think of a scenario where fading a background-image is required. — Eric
– Eric, Commented Jul 31, 2011 at 16:40
Well, I develop online browser games, and there's a few things I'd like to do in the animations that would need this variable-opacity background image. — Niet the Dark Absol
– Niet the Dark Absol, Commented Jul 31, 2011 at 16:42

Gabriele Petrioli · Accepted Answer · 2013-04-12 14:55:09Z

48

You can do the faded background with CSS Generated Content

Demo at http://jsfiddle.net/gaby/WktFm/508/

Html

<div class="container">
        contents
</div>

Css

.container{
    position: relative;
    z-index:1;
    overflow:hidden; /*if you want to crop the image*/
}
.container:before{
    z-index:-1;
    position:absolute;
    left:0;
    top:0;
    content: url('path/to/image.ext');
    opacity:0.4;
}

But you cannot modify the opacity as we are not allowed to modify generated content..

You could manipulate it with classes and css events though (but not sure if it fits your needs)

for example

.container:hover:before{
    opacity:1;
}

UPDATE

You can use css transitions to animate the opacity (again through classes)

demo at http://jsfiddle.net/gaby/WktFm/507/

Adding

-webkit-transition: opacity 1s linear;
-o-transition: opacity 1s linear;
-moz-transition: opacity 1s linear;
transition: opacity 1s linear;

to the .container:before rule will make the opacity animate to 1 in one second.

Compatibility

FF 5 (maybe 4 also, but do not have it installed.)
IE 9 Fails..
Webkit based browsers fail (Chrome supports it now v26 - maybe earlier versions too, but just checked with my current build), but they are aware and working on it ( https://bugs.webkit.org/show_bug.cgi?id=23209 )

.. so only the latest FF supports it for the moment.. but a nice idea, no ? :)

edited Apr 12, 2013 at 14:55

answered Jul 31, 2011 at 18:11

Gabriele Petrioli

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3 Comments

No Results Found Over a year ago

Looks pretty nice to me in FF5, nice job. I completely forgot that pseudo elements have the url property, I tried by using background and couldn't solve the the z-index issues (content beneath).

Niet the Dark Absol Over a year ago

Answer appreciated, but considering how poorly Firefox performs with other things (memory leaks all over the place, horrible lag in JS, it's almost as slow as IE6, certainly slower than IE7...) I will be looking for a more cross-browser solution.

Istiaque Ahmed Over a year ago

@WesleyMurch, may I request you to have a look at a css , jquery question on a different topic at stackoverflow.com/questions/14137378/…

gerardnico · Accepted Answer · 2021-04-28 20:42:20Z

22

Try this

<div style="background: linear-gradient( rgba(0, 0, 0, 0.7), rgba(0, 0, 0, 0.7) ), url(/image.png);background-repeat: no-repeat;  background-position: center;"> </div>

edited Apr 28, 2021 at 20:42

gerardnico

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answered Feb 1, 2019 at 11:25

JM Causing

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4 Comments

klewis Over a year ago

Would love to see the linear-gradient remain in position, even if you change the background-position.

Despertaweb Over a year ago

Yaaay! That's de only true one!! css based only and without any other html tags involved.

velkoon Over a year ago

Woooo! It took hours of googling to find this--thank you so much for posting. I wanted a white overlay/transparency instead of black so I changed rgba(0, 0, 0, 0.7) to rgba(255, 255, 255, 0.7). And it only affects the background instead of the entire element ^__^

Omnik Over a year ago

This is right answer. And you can also make image semi transparent with gradient in its transparency. I turned my pure white lock icon into gray + gradient. Just set colors of background to what you have instead of zeroes.

vsync · Accepted Answer · 2021-06-05 19:49:06Z

21

To set the opacity of a background image, you just need to add an opaque image as first image in the background-image set.

Explanation:

The gradient function is creating an image from a color
The rgba function is creating a color that accepts opacity as parameter (ie alpha parameters)
alpha = 1 - opacity of white
Therefore by combining them, you can create an opaque image.

For instance, you can add an opacity of 0.3 by adding the following image linear-gradient(to right, rgba(255,255,255, 0.7) 0 100%) in the set of background-image

Example for an opacity of 0.3

body{
  background-image: linear-gradient(to right, rgba(255,255,255, 0.7) 0 100%), url(https://images.unsplash.com/photo-1497294815431-9365093b7331?ixid=MnwxMjA3fDB8MHxwaG90by1wYWdlfHx8fGVufDB8fHx8&ixlib=rb-1.2.1&auto=format&fit=crop&w=1950&q=80);
  background-size: cover;
}

Enjoy !

Credits

edited Jun 5, 2021 at 19:49

vsync

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answered Apr 28, 2021 at 18:59

gerardnico

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1 Comment

vsync Over a year ago

it's not opacity, it's simply overlaying a white semi-transparent color on top of the image. This is only useful when the background color behind the image is solid

Saud Alfadhli · Accepted Answer · 2013-03-12 00:32:13Z

18

Try this trick .. use css shadow with (inset) option and make the deep 200px for example

Code:

box-shadow: inset 0px 0px 277px 3px #4c3f37;

.

Also for all browsers:

-moz-box-shadow: inset 0px 0px 47px 3px #4c3f37;
-webkit-box-shadow: inset 0px 0px 47px 3px #4c3f37;
box-shadow: inset 0px 0px 277px 3px #4c3f37;

and increase number to make fill your box :)

Enjoy!

answered Mar 12, 2013 at 0:32

Saud Alfadhli

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2 Comments

RozzA Over a year ago

this does not work for what OP wants but fills my requirements perfectly, thanks!!

sergio Over a year ago

@rozzA the OP didn't state there was another image in the background. In fact he only wanted to know whether it's possible to change the background's opacity, and answered: "NO". This is a nice approach :) but not different to adding a new background with rgba transparency.

Dharman · Accepted Answer · 2024-10-30 19:16:18Z

18

.class {
    /* Fallback for web browsers that doesn't support RGBa */
    background: rgb(0, 0, 0);
    /* RGBa with 0.6 opacity */
    background: rgba(0, 0, 0, 0.6);
}

By Robert Nyman. Copied from: http://robertnyman.com/2010/01/11/css-background-transparency-without-affecting-child-elements-through-rgba-and-filters/

edited Oct 30, 2024 at 19:16

Dharman♦

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answered Jul 30, 2013 at 13:58

anon

2 Comments

Niet the Dark Absol Over a year ago

Maybe I wasn't clear enough. I'm looking to make a background image partially transparent.

Niet the Dark Absol Over a year ago

@sergio This answer tells me how to make a background colour partially transparent. Which is great, except the question - as I stated - is about a background image.

DanMan · Accepted Answer · 2020-11-28 13:50:12Z

17

If the background doesn't have to repeat, you can use the sprite technique (sliding-doors) where you put all the images with differing opacity into one (next to each other) and then just shift them around with background-position.

Or you could declare the same partially transparent background image more than once, if your target browser supports multiple backgrounds (Firefox 3.6+, Safari 1.0+, Chrome 1.3+, Opera 10.5+, Internet Explorer 9+). The opacity of those multiple images should add up, the more backgrounds you define.

This process of combining transparencies is called Alpha Blending and calculated as (thanks @IainFraser):

αᵣ = α₁ + α₂(1-α₁) where α ranges between 0 and 1.

edited Nov 28, 2020 at 13:50

answered Jul 31, 2011 at 15:53

DanMan

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2 Comments

Iain Fraser Over a year ago

One caveat to the multiple-backgrounds technique is that the opacities will multiply rather than add together. If you overlay two 50% opacity images, the result will be one 75% opacity image. Add another one, the opacity jumps to 87.5%, another one 93.75%. Mathematically, the total opacity approaches, but never actually reaches 100%. In practice though, thanks to rounding, you would need a stack of 9 to bring a 50% opacity image to 100%.

Iain Fraser Over a year ago

For those mathematically inclined, here's how you work out what adding another semi-transparent image to a stack will do to the overall opacity: stacked_opacity = current_opacity+((1-current_opacity)*single_opacity) So if our current opacity is 0.25, adding another image will give us 0.4375, thus; 0.25+((1-0.25)*0.25) = 0.4375 Adding another will give us 0.578125, thus; 0.4375+((1-0.4375)*0.25) = 0.578125

Alex K · Accepted Answer · 2014-02-09 07:43:34Z

9

You can put a second element inside the element you wish to have a transparent background on.

<div class="container">
    <div class="container-background"></div>
    <div class="content">
         Yay, happy content!
    </div>
</div>

Then make the '.container-background' positioned absolutely to cover the parent element. At this point you'll be able to adjust the opacity of it without affecting the opacity of the content inside '.container'.

.container {
    position: relative;
}
.container .container-background {
    position: absolute;
    top: 0;
    right: 0;
    bottom: 0;
    left: 0;
    background: url(background.png);
    opacity: 0.5;
}
.container .content {
    position: relative;
    z-index: 1;
}

edited Feb 9, 2014 at 7:43

answered Feb 22, 2013 at 19:24

Alex K

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4 Comments

Niet the Dark Absol Over a year ago

Isn't this exactly the same as the "hack" I used in the question?

Alex K Over a year ago

Hmm... I suppose, but I'm not understanding what's not working for you. I use this method and it works great.

sergio Over a year ago

IT IS EXACTLY as your hack, but because you are reluctant to provide an example and by your comment "@Eric: I'm not referring to any specific case with this, I'm trying to find a general solution to the problem" you seem clear on what you want is not a hack or a workaround that might work for certain scenarios (though you are providing one), but rather the plain answer whether it's possible or not. So the correct answer is "NO, it is not possible as of current CSS specifications". Your problems seem to be some layouts result "complicated" for you. This answer de-complicates it for you.

sergio Over a year ago

I meant exactly as the OP example.

Cokegod · Accepted Answer · 2011-07-31 15:16:17Z

1

You can't edit the image via CSS. The only solution I can think of is to edit the image and change its opacity, or make different images with all the opacities needed.

answered Jul 31, 2011 at 15:16

Cokegod

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1 Comment

sergio Over a year ago

This is the straighter answer, if we forget the OP provided an "alternative", but consider he commented later that he "doesn't want to provide an example" (to provide an alternative). So considering he just wants the answer, here it is :)

user · Accepted Answer · 2014-02-03 00:39:15Z

1

#id {
  position: relative;
  opacity: 0.99;
}

#id::before {
  content: "";
  position: absolute;
  width: 100%;
  height: 100%;
  z-index: -1;
  background: url('image.png');
  opacity: 0.3;
}

Hack with opacity 0.99 (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.

edited Feb 3, 2014 at 0:39

answered Feb 2, 2014 at 22:44

user

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6 Comments

user Over a year ago

@bjb568 Yeah, that was my first thought. But it doesn't really work as translucent background, acting as translucent foreground instead. Try to add an image inside of block or change text color to background color (white) and you'll see.

user Over a year ago

@bjb568 Yup, in your example you can see the should-be-background over the inner image. Try to increase opacity of the "background" element, and you'll see how inner image fades away.

user Over a year ago

@bjb568 Have you ever wondered why you had to add no-repeat? You think your version is ok because the element is fixed size that is equal to the bg image size, and because you don't have any parent element with background (background-color would suffice).

user Over a year ago

@bjb568 I gave thorough example. If you think it has redundancy, start with it and try to remove anything. You'll see that each parameter has it's place. If you think you've found an another technique, please post it as another answer.

bjb568 Over a year ago

I have wondered. I can also do it without weird hacks. No-repeat is for... it not repeating. Ok, fine. Another answer, then.

|

Stanislav · Accepted Answer · 2016-07-24 21:31:30Z

Here is another approach to setup gradient and stransparency with CSS. You need to play arround with the parameters a bit though.

background-image: -webkit-gradient(linear, left top, left bottom, color-stop(0%, rgba(0, 0, 0, 0)), color-stop(100%, transparent)),url("gears.jpg"); /* Chrome,Safari4+ */
background-image: -webkit-linear-gradient(top, transparent, transparent),url("gears.jpg"); /* Chrome10+,Safari5.1+ */
background-image:    -moz-linear-gradient(top, transparent, transparent),url("gears.jpg"); /* FF3.6+ */
background-image:     -ms-linear-gradient(top, transparent, transparent),url("gears.jpg"); /* IE10+ */
background-image:      -o-linear-gradient(top, transparent, transparent),url("gears.jpg"); /* Opera 11.10+ */
background-image:         linear-gradient(to bottom, transparent, transparent),url("gears.jpg"); /* W3C */

איש נחמד · Accepted Answer · 2021-04-14 19:36:25Z

1

I use it, I tested it on a white background, but it can be matched to the background color, especially if using css var:

background: #ececec99;
background-blend-mode: lighten;
background-image: url(images/background-1.jpg);
background-repeat: no-repeat;
background-size: cover;
background-position: center;

It's important to note that I only checked this in the Chrome browser.

answered Apr 14, 2021 at 19:36

איש נחמד

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Comments

Pars · Accepted Answer · 2021-08-19 09:46:09Z

1

You can use a hack to achieve a filter effect. some users mentioned before but none of their answers worked for me except this solution

#item_with_background {
    background: rgb(filter_color) url(...)
}

#item_with_background > * {
    position: relative;
    z-index: 1; // this may cause other problems if you have other elements with higher than 1 z-index. so use with caution.
}

#item_with_background::before {
    content: ' ';
    position: absolute;
    top: 0;
    bottom: 0;
    left: 0;
    right: 0;
    background: rgba(filter_color, 0.9);
    width: 100%;
    height: 100%;
    z-index: 0;
}

Here is a working example

answered Aug 19, 2021 at 9:46

Pars

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Ali Silva · Accepted Answer · 2017-06-30 07:33:13Z

-1

body {
  ' css code that goes in your body'
}

body::after {
  background: url(yourfilename.jpg);
  content: "";
  opacity: 0.6;
  position: fixed;
  top: 0;
  bottom: 0;
  right: 0;
  left: 0;
  z-index: -1;   
  width:auto;
  height: 100%;
  }

So to say its the body::after you are looking for. This way the code for your body is not changed or altered only the background where you can make changes where necessary.

answered Jun 30, 2017 at 7:33

Ali Silva

1

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