image-rendering

The image-rendering CSS property sets an image scaling algorithm. The property applies to an element itself, to any images set in its other properties, and to its descendants.

The user agent will scale an image when the page author specifies dimensions other than its natural size. Scaling may also occur due to user interaction (zooming). For example, if the natural size of an image is 100×100px, but its actual dimensions are 200×200px (or 50×50px), then the image will be upscaled (or downscaled) using the algorithm specified by image-rendering. This property has no effect on non-scaled images.

Syntax

/* Keyword values */
image-rendering: auto;
image-rendering: crisp-edges;
image-rendering: pixelated;

/* Global values */
image-rendering: inherit;
image-rendering: initial;
image-rendering: revert;
image-rendering: unset;

Values

auto: The scaling algorithm is UA dependent. Since version 1.9 (Firefox 3.0), Gecko uses bilinear resampling (high quality).
smooth: The image should be scaled with an algorithm that maximizes the appearance of the image. In particular, scaling algorithms that "smooth" colors are acceptable, such as bilinear interpolation. This is intended for images such as photos.
high-quality: Identical to smooth, but with a preference for higher-quality scaling. If system resources are constrained, images with high-quality should be prioritized over those with any other value, when considering which images to degrade the quality of and to what degree.
crisp-edges: The image is scaled with the nearest-neighbor algorithm.
pixelated: Using the nearest-neighbor algorithm, the image is scaled up to the next integer multiple that is greater than or equal to its original size, then scaled down to the target size, as for smooth. When scaling up to integer multiples of the original size, this will have the same effect as crisp-edges.

Note: The values optimizeQuality and optimizeSpeed present in an early draft (and coming from its SVG counterpart image-rendering) are defined as synonyms for the smooth and pixelated values respectively.

Formal definition

Initial value	`auto`
Applies to	all elements
Inherited	yes
Computed value	as specified
Animation type	discrete

Formal syntax

auto | crisp-edges | pixelated

Examples

Setting image scaling algorithms

In practical use, the pixelated and crisp-edges rules can be combined to provide some fallback for each other. (Just prepend the actual rules with the fallback.) The Canvas API can provide a fallback solution for pixelated through manual image data manipulation or with imageSmoothingEnabled.

<div>
  <img class="auto" alt="auto" src="blumen.jpg" />
  <img class="pixelated" alt="pixelated" src="blumen.jpg" />
  <img class="crisp-edges" alt="crisp-edges" src="blumen.jpg" />
</div>

img {
  height: 200px;
}

CSS

.auto {
  image-rendering: auto;
}

.pixelated {
  -ms-interpolation-mode: nearest-neighbor;
  image-rendering: pixelated;
}

.crisp-edges {
  image-rendering: -webkit-optimize-contrast;
  image-rendering: crisp-edges;
}

Result

Specifications

Specification
CSS Images Module Level 3 # the-image-rendering

Browser compatibility

BCD tables only load in the browser

Note: Although crisp-edges is supposed to use a pixel-art scaler like in the specification example, in practice no browsers (as of January 2020) do so. In Firefox, crisp-edges is interpreted as nearest-neighbor, pixelated is not supported, and auto is interpolated as trilinear or linear.

For behavior on Chromium and Safari (WebKit), see the GetInterpolationQuality function and CSSPrimitiveValue::operator ImageRendering() respectively.