astro/packages/integrations/image/README.md

@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?
• Installation
• Usage
• Configuration
• Examples
• Troubleshooting
• Contributing
• Changelog

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 powered by sharp, with full support for static sites and server-side rendering. The built-in sharp transformer is also replacable, opening the door for future integrations that work with your favorite hosted image service.

Installation

Quick Install

The 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.

# Using NPM
npx astro add image
# Using Yarn
yarn astro add image
# Using PNPM
pnpx astro add image

Then, restart the dev server by typing CTRL-C and then npm run astro dev in the terminal window that was running Astro.

Because this command is new, it might not properly set things up. If that happens, feel free to log an issue on our GitHub and try the manual installation steps below.

Manual Install

First, install the @astrojs/image package using your package manager. If you're using npm or aren't sure, run this in the terminal:

npm install @astrojs/image

Then, apply this integration to your astro.config.* file using the integrations property:

astro.config.mjs

import image from '@astrojs/image';

export default {
  // ...
  integrations: [image()],
}

Then, restart the dev server.

Update tsconfig.json

For the best development experience, add the integrations type definitions to your project's tsconfig.json file.

{
  "compilerOptions": {
    // Replace `astro/client` with `@astrojs/image/client`
    "types": ["@astrojs/image/client"]
  }
}

Usage

The included sharp transformer supports 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).

<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 />.

src

Type: string | ImageMetadata | Promise<ImageMetadata>
Required: true

Source for the original image file.

For images in your project's repository, use the src relative to the public directory. For remote images, provide the full URL.

format

Type: '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.

quality

Type: number
Default: undefined

The compression quality used during optimization. The image service will use a default quality if not provided.

width

Type: 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

Type: 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

Type: 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}.

<Picture />

src

Type: string | ImageMetadata | Promise<ImageMetadata>
Required: true

Source for the original image file.

For images in your project's repository, use the src relative to the public directory. For remote images, provide the full URL.

alt

Type: string
Default: undefined

If provided, the alt string will be included on the built <img /> element.

sizes

Type: 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

Type: 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.

// Builds three images: 400x400, 800x800, and 1200x1200
<Picture src={...} widths={[400, 800, 1200]} aspectRatio="1:1" />

aspectRatio

Type: number | string
Required: true

The desired aspect ratio of the output image. This is combined with widhts 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}.

formats

Type: 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.

getImage

This 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 helpful if you need to add preload links to a page's <head>.

---
import { getImage } from '@astrojs/image';

const { src } = await getImage('../assets/hero.png');
---

<html>
  <head>
    <link rel="preload" as="image" href={src}>
  </head>
</html>

getPicture

This 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

The intergration 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 sharp service when using astro dev.

There are currently no other configuration options for the @astrojs/image integration. Please open an issue if you have a compelling use case to share.

config.serviceEntryPoint

The serviceEntryPoint should resolve to the image service installed from NPM. The default entry point is @astrojs/image/sharp, which resolves to the entry point exported from this integration's package.json.

// astro.config.mjs
import image from '@astrojs/image';

export default {
  integrations: [image({
    // Example: The entrypoint for a third-party image service installed from NPM
    serviceEntryPoint: 'my-image-service/astro.js'
  })],
}

Examples

Local images

Image files in your project's src directory can be imported in frontmatter and passed directly to the <Image /> component. All other properties are optional and will default to the original image file's properties if not provided.

---
import { Image } from '@astrojs/image/components';
import heroImage from '../assets/hero.png';
---

// optimized image, keeping the original width, height, and image format
<Image src={heroImage} />

// height will be recalculated to match the original aspect ratio
<Image src={heroImage} width={300} />

// cropping to a specific width and height
<Image src={heroImage} width={300} height={600} />

// cropping to a specific aspect ratio and converting to an avif format
<Image src={heroImage} aspectRatio="16:9" format="avif" />

// image imports can also be inlined directly
<Image src={import('../assets/hero.png')} />

Remote images

Remote 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.

---
import { Image } from '@astrojs/image/components';

const imageUrl = 'https://www.google.com/images/branding/googlelogo/2x/googlelogo_color_272x92dp.png';
---

// cropping to a specific width and height
<Image src={imageUrl} width={544} height={184} />

// height will be recalculated to match the aspect ratio
<Image src={imageUrl} width={300} aspectRatio={16/9} />

// cropping to a specific height and aspect ratio and converting to an avif format
<Image src={imageUrl} height={200} aspectRatio="16:9" format="avif" />

Responsive pictures

The <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 in addition to the image's original format.

For remote images, an aspectRatio is required to ensure the correct height can be calculated at build time.

---
import { Picture } from '@astrojs/image/components';
import hero from '../assets/hero.png';

const imageUrl = 'https://www.google.com/images/branding/googlelogo/2x/googlelogo_color_272x92dp.png';
---

// Local image with multiple sizes
<Picture src={hero} widths={[200, 400, 800]} sizes="(max-width: 800px) 100vw, 800px" alt="My hero image" />

// Remote image (aspect ratio is required)
<Picture src={imageUrl} widths={[200, 400, 800]} aspectRatio="4:3" sizes="(max-width: 800px) 100vw, 800px" alt="My hero image" />

// Inlined imports are supported
<Picture src={import("../assets/hero.png")} widths={[200, 400, 800]} sizes="(max-width: 800px) 100vw, 800px" alt="My hero image" />

Troubleshooting

• If your installation doesn't seem to be working, make sure to restart the dev server.
• If you edit and save a file and don't see your site update accordingly, try refreshing the page.
• 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-threads 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

This package is maintained by Astro's Core team. You're welcome to submit an issue or PR!

Changelog

See CHANGELOG.md for a history of changes to this integration.