CSS adjust brightness of image background and not content
<p>The section has a background image with content on top.
I want to decrease the brightness of only the background image in the section and not the content.</p>

<p>I have tried the below, however, the brightness still applies to all and not just the image.</p>

<pre><code>&lt;!-- Section --&gt;
&lt;div id="section1"&gt;
    &lt;div id="content"&gt;



    &lt;h1 class="heading"&gt;headline text&lt;/h1&gt;
    &lt;h4 class="subHeading"&gt; Sub-headline text&lt;/h4&gt;

    &lt;!-- Call to action button --&gt;
    &lt;br&gt;&lt;br&gt;
    &lt;button&gt; Join our wait list &lt;/button&gt;

&lt;/div&gt;
</code></pre>

<p></p>

<pre><code>#section1 {
background: url('../images/headerimage1.jpg') center center no-repeat;
background-size: cover;
-webkit-filter: brightness(0.5);
filter: brightness(0.5);
    padding-top: 100px;
    padding-bottom: 100px;
    padding-left: 10%;
    padding-right: 10%;
    color: white;
    text-align: center;
}

#content {
  -webkit-filter: brightness(1);
filter: brightness(1);
}
</code></pre>