contrast()

The contrast() CSS function adjusts the contrast of the input image. Its result is a <filter-function>.

Syntax

css

contrast(amount)

Values

amount: The contrast of the result, specified as a <number> or a <percentage>. A value under 100% decreases the contrast, while a value over 100% increases it. A value of 0 or 0% will create an image that is completely gray, while a value of 1 or 100% leaves the input unchanged. Negative values are not allowed. The initial value for interpolation is 1.

The following are pairs of equivalent values:

css

contrast(0) /* Completely gray */
contrast(0%)

contrast(0.65) /* 65% contrast */
contrast(65%)

contrast(1)     /* No effect */
contrast(100%)

contrast(2)  /* Double contrast */
contrast(200%)

Formal syntax

<contrast()> = 
  contrast( [ <number> | <percentage> ]? )

Examples

With the backdrop-filter property

This example applies a contrast() filter via the backdrop-filter CSS property to the paragraph and monospaced text, color shifting to the area behind the <p> and <code>.

css

.container {
  background: url(image.jpg) no-repeat center / contain #339;
}
p {
  backdrop-filter: contrast(0.5);
}
code {
  backdrop-filter: contrast(0.15);
}

.container {
  padding: 3rem;
  width: 30rem;
}
p {
  padding: 0.5rem;
  color: #ffffff;
  font-family: sans-serif;
}

<div class="container" style="background-image: url(unity_for_the_people.jpg);">
  <p>
    Alway ensure there is enough contrast between text and all background
    colors. If you think your text may land on top of a background image,
    include a <code>backdrop-filter</code>. Reducing the contrast of background
    colors with the <code>contrast()</code> filter may improve legibility but
    does not guarantee accessibility.
  </p>
</div>

With the filter property

This example applies a contrast() filter via the filter CSS property, changing contrast by shifting colors of the entire element, including content, border, background, and shadows.

css

p:first-of-type {
  filter: contrast(30%);
}
p:last-of-type {
  filter: contrast(300%);
}

p {
  text-shadow: 2px 2px blue;
  background-color: magenta;
  color: palegoldenrod;
  border: 1em solid rebeccapurple;
  box-shadow: inset -5px -5px red, 5px 5px yellow;
  padding: 0.25rem;
  font-size: 1.25rem;
  font-family: sans-serif;
  width: 85vw;
}

<p>This paragraph has reduced contrast.</p>
<p>This paragraph has normal contrast.</p>
<p>This paragraph has increased contrast.</p>

With url() and the SVG contrast filter

The SVG <filter> element is used to define custom filter effects that can then be referenced by id. The <filter>'s <feComponentTransfer> primitive enables pixel-level color remapping. Given the following:

svg

  <filter id="contrast">
    <feComponentTransfer>
      <feFuncR type="linear" slope="2" intercept="-0.5"/>
      <feFuncG type="linear" slope="2" intercept="-0.5"/>
      <feFuncB type="linear" slope="2" intercept="-0.5"/>
    </feComponentTransfer>
  </filter>

.svgFilterLive {
  filter: url(#contrast2);
}

These values produce the same results:

css

filter: contrast(200%);
filter: url(#contrast); /* with embedded SVG */
filter: url(folder/fileName.svg#contrast); /* external svg filter definition */

This example shows three images: the image with a contrast() filter function applied, the image with an equivalent url() filter applied, and the original images for comparison:

<table cellpadding="5">
  <thead>
    <tr>
      <th><code>contrast()</code></th>
      <th><code>url()</code></th>
      <th>Original image</th>
    </tr>
  </thead>
  <tbody>
    <tr>
      <td>
        <img style="filter: contrast(200%)" src="flag.jpg" alt="Pride flag" />
      </td>
      <td>
        <img class="svgFilterLive" src="flag.jpg" alt="Pride flag" />
        <svg
          xmlns="http://www.w3.org/2000/svg"
          id="svg"
          viewBox="0 0 240 151"
          height="0"
          width="0"
          style="overflow: visible"
          color-interpolation-filters="sRGB">
          <filter id="contrast2">
            <feComponentTransfer>
              <feFuncR type="linear" slope="2" intercept="-0.5" />
              <feFuncG type="linear" slope="2" intercept="-0.5" />
              <feFuncB type="linear" slope="2" intercept="-0.5" />
            </feComponentTransfer>
          </filter>
        </svg>
      </td>
      <td>
        <img src="flag.jpg" alt="Pride flag" />
      </td>
    </tr>
  </tbody>
</table>

Specifications

Specification
Filter Effects Module Level 1 # funcdef-filter-contrast

Browser compatibility

BCD tables only load in the browser