dynamic-range-limit-mix()

Syntax

dynamic-range-limit-mix(standard 70%, no-limit 30%);
dynamic-range-limit-mix(no-limit 10%, constrained 20%);
dynamic-range-limit-mix(no-limit 30%, constrained 30%, standard 30%);
dynamic-range-limit-mix(
    no-limit 20%,
    dynamic-range-limit-mix(standard 25%, constrained 75%) 20%
)

Parameters

dynamic-range-limit <percentage>

A pair consisting of a dynamic-range-limit value (which can be another dynamic-range-limit-mix() function) and a <percentage> between 0% and 100% (inclusive). The <percentage> specifies the proportion of a dynamic-range-limit keyword value in the custom limit. The dynamic-range-limit-mix() function can take two or more of these pairs as parameters.

Return value

A custom maximum luminance limit, expressed as a number of photographic stops higher than the HDR reference white. For privacy reasons, the actual calculated result is not exposed.

Description

The dynamic-range-limit property allows you to control the brightness of High Dynamic Range (HDR) content. The dynamic-range-limit-mix() function can be provided as a value of dynamic-range-limit, and enables you to create custom brightness limits by mixing together percentages of the dynamic-range-limit keyword values.

Calculating the percentages

When the given percentages add up to 100%, the result is obvious:

/* standard 70%, no-limit 30% */
dynamic-range-limit-mix(standard 70%, no-limit 30%);

When the given percentages do not add up to 100%, the resulting percentages are equal to the given percentages expressed proportionately to one another so the total equals 100%:

/* no-limit 40%, constrained 60% */
dynamic-range-limit-mix(no-limit 20%, constrained 30%);

/* no-limit 20%, constrained 40%, standard 40% */
dynamic-range-limit-mix(no-limit 40%, constrained 80%, standard 80%);

If a dynamic-range-limit keyword value is used more than once, the percentages for that keyword value are added together to get the total percentage:

/* constrained 70%, standard 30% */
dynamic-range-limit-mix(constrained 40%, standard 30%, constrained 30%);

/* no-limit 40%, constrained 60% */
dynamic-range-limit-mix(no-limit 10%, constrained 30%, no-limit 10%);

If a specified percentage is less than 0% or greater than 100%, the dynamic-range-limit-mix() function — and therefore the associated dynamic-range-limit property value — is invalid. If a keyword is used more than once and the cumulative percentage is more than 100%, the value is valid, and the proportion rules described above come into play.

Nesting dynamic-range-limit-mix() functions

You can nest dynamic-range-limit-mix() functions inside one another. When doing so, the same rules explained earlier apply, and each set of percentages is calculated separately and then added. In the following example:

dynamic-range-limit-mix(
    no-limit 10%,
    dynamic-range-limit-mix(standard 25%, constrained 75%) 20%,
    dynamic-range-limit-mix(constrained 10%, no-limit 30%) 20%
)

• The first line gives us no-limit 10%.
• Since 25% and 75% add up to 100%, the second line gives us standard 5% (25% of 20%) and constrained 15% (75% of 20%).
• In the third line, because 10% and 30% add up to only 40%, not 100%, we normalize both as proportions of 40%: 10/40=25% and 30/40=75%. This gives us constrained 5% (25% of 20%) and no-limit 15% (75% of 20%).

Adding these up to get the raw percentages gives us:

dynamic-range-limit-mix(standard 5%, constrained 20%, no-limit 25%)

The above percentages add up to 50%, so they need to be doubled to get the final percentages. The computed value is therefore:

dynamic-range-limit-mix(standard 10%, constrained 40%, no-limit 50%)

Formal syntax

<dynamic-range-limit-mix()> = 
  dynamic-range-limit-mix( [ <'dynamic-range-limit'> && <percentage [0,100]> ]#{2,} )  

<dynamic-range-limit> = 
  standard                     |
  no-limit                     |
  constrained                  |
  <dynamic-range-limit-mix()>  

Examples

Basic usage

Consider an <img> element being used to embed an HDR image on a web page:

<img src="my-hdr-image.jpg" alt="my image" />

On HDR displays, the brightest areas of the image could prove to be jarring and uncomfortable to look at. To solve this problem, we could set the image's dynamic-range-limit property to dynamic-range-limit-mix(standard 70%, no-limit 30%), which gives it a maximum luminance limit of only slightly brighter than HDR reference white:

img {
  dynamic-range-limit: dynamic-range-limit-mix(standard 70%, no-limit 30%);
}

You can see the dynamic-range-limit property in action in our dynamic-range-limit property demo, which includes an HDR image that can be hovered and focused to transition the dynamic-range-limit value. View the example live in a display capable of displaying HDR colors, and try it out.

Specifications

Browser compatibility

See also

• dynamic-range-limit