@astrojs/image
⚠️ This integration is still experimental! Only node environments are supported currently, stay tuned for Deno support in the future!
This Astro integration makes it easy to optimize images in your Astro project, with full support for SSG builds and server-side rendering!
Why @astrojs/image
?
Section titled Why @astrojs/image?Images play a big role in overall site performance and usability. Serving properly sized images makes all the difference but is often tricky to automate.
This integration provides <Image />
and <Picture>
components as well as a basic image transformer, with full support for static sites and server-side rendering. The built-in image transformer is also replaceable, opening the door for future integrations that work with your favorite hosted image service.
Installation
Section titled InstallationAlong with our integration, we recommend installing sharp when appropriate.
The @astrojs/image
default image transformer is based on Squoosh and uses WebAssembly libraries to support most deployment environments, including those that do not support sharp, such as StackBlitz.
For faster builds and more fine-grained control of image transformations, install sharp in addition to @astrojs/image
if
- You are building a static site with Astro.
- You are using an SSR deployment host that supports NodeJS using
@astrojs/netlify/functions
,@astrojs/vercel/serverless
or@astrojs/node
.
Note that @astrojs/image
is not currently supported on
- Cloudflare SSR
@astrojs/deno
@astrojs/netlify/edge-functions
@astrojs/vercel/edge
Quick Install
Section titled Quick InstallThe astro add
command-line tool automates the installation for you. Run one of the following commands in a new terminal window. (If you aren’t sure which package manager you’re using, run the first command.) Then, follow the prompts, and type “y” in the terminal (meaning “yes”) for each one.
If you run into any issues, feel free to report them to us on GitHub and try the manual installation steps below.
Manual Install
Section titled Manual InstallFirst, install the @astrojs/image
package using your package manager. If you’re using npm or aren’t sure, run this in the terminal:
Then, apply this integration to your astro.config.*
file using the integrations
property:
Installing sharp
(optional)
Section titled Installing sharp (optional)First, install the sharp
package using your package manager. If you’re using npm or aren’t sure, run this in the terminal:
Then, update the integration in your astro.config.*
file to use the built-in sharp
image transformer.
Update env.d.ts
Section titled Update env.d.tsFor the best development experience, add the integrations type definitions to your project’s env.d.ts
file.
Or, alternatively if your project is using the types through a tsconfig.json
Usage
Section titled UsageThe included image transformers support resizing images and encoding them to different image formats. Third-party image services will be able to add support for custom transformations as well (ex: blur
, filter
, rotate
, etc).
Astro’s <Image />
and <Picture />
components require the alt
attribute, which provides descriptive text for images. A warning will be logged if alt text is missing, and a future release of the integration will throw an error if no alt text is provided.
If the image is merely decorative (i.e. doesn’t contribute to the understanding of the page), set alt=""
so that the image is properly understood and ignored by screen readers.
<Image />
Section titled <Image />The built-in <Image />
component is used to create an optimized <img />
for both remote images hosted on other domains as well as local images imported from your project’s src
directory.
In addition to the component-specific properties, any valid HTML attribute for the <img />
included in the <Image />
component will be included in the built <img />
.
Type: string
| ImageMetadata
| Promise<ImageMetadata>
Required: true
Source for the original image file.
For images located in your project’s src
: use the file path relative to the src
directory. (e.g. src="../assets/source-pic.png"
)
For images located in your public
directory: use the URL path relative to the public
directory. (e.g. src="/images/public-image.jpg"
)
For remote images, provide the full URL. (e.g. src="https://astro.build/assets/blog/astro-1-release-update.avif"
)
Type: string
Required: true
Defines an alternative text description of the image.
Set to an empty string (alt=""
) if the image is not a key part of the content (e.g. it’s decoration or a tracking pixel).
format
Section titled formatType: 'avif' | 'jpeg' | 'png' | 'webp'
Default: undefined
The output format to be used in the optimized image. The original image format will be used if format
is not provided.
This property is required for remote images only, because the original format cannot be inferred.
quality
Section titled qualityType: number
Default: undefined
The compression quality used during optimization. The image service will use its own default quality depending on the image format if not provided.
width
Section titled widthType: number
Default: undefined
The desired width of the output image. Combine with height
to crop the image to an exact size, or aspectRatio
to automatically calculate and crop the height.
Dimensions are optional for local images, the original image size will be used if not provided.
For remote images, the integration needs to be able to calculate dimensions for the optimized image. This can be done by providing width
and height
or by providing one dimension and an aspectRatio
.
height
Section titled heightType: number
Default: undefined
The desired height of the output image. Combine with width
to crop the image to an exact size, or aspectRatio
to automatically calculate and crop the width.
Dimensions are optional for local images, the original image size will be used if not provided.
For remote images, the integration needs to be able to calculate dimensions for the optimized image. This can be done by providing width
and height
or by providing one dimension and an aspectRatio
.
aspectRatio
Section titled aspectRatioType: number
| string
Default: undefined
The desired aspect ratio of the output image. Combine with either width
or height
to automatically calculate and crop the other dimension.
A string
can be provided in the form of {width}:{height}
, ex: 16:9
or 3:4
.
A number
can also be provided, useful when the aspect ratio is calculated at build time. This can be an inline number such as 1.777
or inlined as a JSX expression like aspectRatio={16/9}
.
background
Section titled backgroundType: ColorDefinition
Default: undefined
This is not supported by the default Squoosh service. See the installation section for details on using the
sharp
service instead.
The background color is used to fill the remaining background when using contain
for the fit
property.
The background color is also used for replacing the alpha channel with sharp
’s flatten
method. In case the output format
doesn’t support transparency (i.e. jpeg
), it’s advisable to include a background color, otherwise black will be used
as default replacement for transparent pixels.
The parameter accepts a string
as value.
The parameter can be a named HTML color, a hexadecimal
color representation with 3 or 6 hexadecimal characters in the form #123[abc]
, an RGB definition in the form
rgb(100,100,100)
, an RGBA definition in the form rgba(100,100,100, 0.5)
.
Type: 'cover' | 'contain' | 'fill' | 'inside' | 'outside'
Default: 'cover'
This is not supported by the default Squoosh service. See the installation section for details on using the
sharp
service instead.
How the image should be resized to fit both height
and width
.
position
Section titled positionType: 'top' | 'right top' | 'right' | 'right bottom' | 'bottom' | 'left bottom' | 'left' | 'left top' | 'north' | 'northeast' | 'east' | 'southeast' | 'south' | 'southwest' | 'west' | 'northwest' | 'center' | 'centre' | 'cover' | 'entropy' | 'attention'
Default: 'centre'
This is not supported by the default Squoosh service. See the installation section for details on using the
sharp
service instead.
Position of the crop when fit is cover
or contain
.
<Picture />
Section titled <Picture />The built-in <Picture />
component is used to create an optimized <picture />
for both remote images hosted on other domains as well as local images imported from your project’s src
directory.
In addition to the component-specific properties, any valid HTML attribute for the <img />
included in the <Picture />
component will be included in the built <img />
.
Type: string
| ImageMetadata
| Promise<ImageMetadata>
Required: true
Source for the original image file.
For images located in your project’s src
: use the file path relative to the src
directory. (e.g. src="../assets/source-pic.png"
)
For images located in your public
directory: use the URL path relative to the public
directory. (e.g. src="/images/public-image.jpg"
)
For remote images, provide the full URL. (e.g. src="https://astro.build/assets/blog/astro-1-release-update.avif"
)
Type: string
Required: true
Defines an alternative text description of the image.
Set to an empty string (alt=""
) if the image is not a key part of the content (e.g. it’s decoration or a tracking pixel).
sizes
Section titled sizesType: string
Required: true
The HTMLImageElement property sizes
allows you to specify the layout width of the image for each of a list of media conditions.
See MDN for more details.
widths
Section titled widthsType: number[]
Required: true
The list of sizes that should be built for responsive images. This is combined with aspectRatio
to calculate the final dimensions of each built image.
aspectRatio
Section titled aspectRatioType: number
| string
Default: undefined
The desired aspect ratio of the output image. This is combined with widths
to calculate the final dimensions of each built image.
A string
can be provided in the form of {width}:{height}
, ex: 16:9
or 3:4
.
A number
can also be provided, useful when the aspect ratio is calculated at build time. This can be an inline number such as 1.777
or inlined as a JSX expression like aspectRatio={16/9}
.
For remote images only, aspectRatio
is required to ensure the correct height
can be calculated at build time.
formats
Section titled formatsType: Array<'avif' | 'jpeg' | 'png' | 'webp'>
Default: undefined
The output formats to be used in the optimized image. If not provided, webp
and avif
will be used in addition to the original image format.
For remote images, the original image format is unknown. If not provided, only webp
and avif
will be used.
background
Section titled backgroundType: ColorDefinition
Default: undefined
This is not supported by the default Squoosh service. See the installation section for details on using the
sharp
service instead.
The background color to use for replacing the alpha channel with sharp
’s flatten
method. In case the output format
doesn’t support transparency (i.e. jpeg
), it’s advisable to include a background color, otherwise black will be used
as default replacement for transparent pixels.
The parameter accepts a string
as value.
The parameter can be a named HTML color, a hexadecimal
color representation with 3 or 6 hexadecimal characters in the form #123[abc]
, or an RGB definition in the form
rgb(100,100,100)
.
Type: 'cover' | 'contain' | 'fill' | 'inside' | 'outside'
Default: 'cover'
This is not supported by the default Squoosh service. See the installation section for details on using the
sharp
service instead.
How the image should be resized to fit both height
and width
.
position
Section titled positionType: 'top' | 'right top' | 'right' | 'right bottom' | 'bottom' | 'left bottom' | 'left' | 'left top' | 'north' | 'northeast' | 'east' | 'southeast' | 'south' | 'southwest' | 'west' | 'northwest' | 'center' | 'centre' | 'cover' | 'entropy' | 'attention'
Default: 'centre'
This is not supported by the default Squoosh service. See the installation section for details on using the
sharp
service instead.
Position of the crop when fit is cover
or contain
.
getImage
Section titled getImageThis is the helper function used by the <Image />
component to build <img />
attributes for the transformed image. This helper can be used directly for more complex use cases that aren’t currently supported by the <Image />
component.
This helper takes in an object with the same properties as the <Image />
component and returns an object with attributes that should be included on the final <img />
element.
This can be helpful if you need to add preload links to a page’s <head>
.
getPicture
Section titled getPictureThis is the helper function used by the <Picture />
component to build multiple sizes and formats for responsive images. This helper can be used directly for more complex use cases that aren’t currently supported by the <Picture />
component.
This helper takes in an object with the same properties as the <Picture />
component and returns an object attributes that should be included on the final <img />
element and a list of sources that should be used to render all <source>
s for the <picture>
element.
Configuration
Section titled ConfigurationThe integration can be configured to run with a different image service, either a hosted image service or a full image transformer that runs locally in your build or SSR deployment.
During development, local images may not have been published yet and would not be available to hosted image services. Local images will always use the built-in image service when using
astro dev
.
config.serviceEntryPoint
Section titled config.serviceEntryPointThe serviceEntryPoint
should resolve to the image service installed from NPM. The default entry point is @astrojs/image/squoosh
, which resolves to the entry point exported from this integration’s package.json
.
config.logLevel
Section titled config.logLevelThe logLevel
controls can be used to control how much detail is logged by the integration during builds. This may be useful to track down a specific image or transformation that is taking a long time to build.
config.cacheDir
Section titled config.cacheDirDuring static builds, the integration will cache transformed images to avoid rebuilding the same image for every build. This can be particularly helpful if you are using a hosting service that allows you to cache build assets for future deployments.
Local images will be cached for 1 year and invalidated when the original image file is changed. Remote images will be cached based on the fetch()
response’s cache headers, similar to how a CDN would manage the cache.
By default, transformed images will be cached to ./node_modules/.astro/image
. This can be configured in the integration’s config options.
Caching can also be disabled by using cacheDir: false
.
Examples
Section titled ExamplesLocal images
Section titled Local imagesImage files in your project’s src/
directory can be imported in frontmatter and passed directly to the <Image />
component as the src=
attribute value. alt
is also required.
All other properties are optional and will default to the original image file’s properties if not provided.
Images in /public
Section titled Images in /publicThe <Image />
component can also be used with images stored in the public/
directory and the src=
attribute is relative to the public folder. It will be treated as a remote image, which requires either both width
and height
, or one dimension and an aspectRatio
attribute.
Your original image will be copied unprocessed to the build folder, like all files located in public/, and Astro’s image integration will also return optimized versions of the image.
For example, use an image located at public/social.png
in either static or SSR builds like so:
Remote images
Section titled Remote imagesRemote images can be transformed with the <Image />
component. The <Image />
component needs to know the final dimensions for the <img />
element to avoid content layout shifts. For remote images, this means you must either provide width
and height
, or one of the dimensions plus the required aspectRatio
.
Responsive pictures
Section titled Responsive picturesThe <Picture />
component can be used to automatically build a <picture>
with multiple sizes and formats. Check out MDN for a deep dive into responsive images and art direction.
By default, the picture will include formats for avif
and webp
. For local images only, the image’s original format will also be included.
For remote images, an aspectRatio
is required to ensure the correct height
can be calculated at build time.
Troubleshooting
Section titled Troubleshooting- If your installation doesn’t seem to be working, try restarting the dev server.
- If you edit and save a file and don’t see your site update accordingly, try refreshing the page.
- If refreshing the page doesn’t update your preview, or if a new installation doesn’t seem to be working, then restart the dev server.
For help, check out the #support
channel on Discord. Our friendly Support Squad members are here to help!
You can also check our Astro Integration Documentation for more on integrations.
Contributing
Section titled ContributingThis package is maintained by Astro’s Core team. You’re welcome to submit an issue or PR!
Changelog
Section titled ChangelogSee CHANGELOG.md for a history of changes to this integration.