Photon

Photon is an image acceleration and editing service for sites hosted on WordPress.com or on Jetpack-connected WordPress sites. That means less load on your host and faster images for your readers.

To start using Photon:

1. From the Jetpack page in your blog dashboard, click the Activate button for Photon.
2. You’re done! Your images will now be served dynamically from the global WordPress.com cloud.

Need some help?

• How Photon Works
• Questions & Answers
• Limitations

How Photon Works

• Photon filters content but doesn’t change the info in the database.
• Photon currently only acts on images in posts and pages, as well as featured images/post thumbnails via the image_downsize filter.
• Photon will apply to old posts and new ones alike and can be turned on or off easily.

Questions & Answers

• How does Photon determine which dimensions to serve?
  Photon looks at the img element’s width and height attributes and then serves an image resized to those dimensions or to the width of the containing element (whichever is smaller).
• Is there any way to keep the “width” and “height” attributes in the Photon-generated HTML?
  We remove the width and height arguments to prevent your images from skewing when the resized image doesn’t have the same dimensions as the original. This is particularly important when you switch from one theme to another, and the new theme is narrower than the previous theme. One of the benefits of Photon is that it will automatically resize your images so they don’t exceed the width supported by your theme.

Limitations

• No cache invalidations – currently the images are cached “forever”. If you want to “refresh” an image you will need to change the name of the image. Adding random query arguments, commonly known as cachebusters, will not work.
• We only fetch, resize, and serve gif, png, and jpg images from servers that listen on port 80. This is about 99.99% of the web servers in the world.
• We will not “upscale” an image in most circumstances. If your original image is 1000px wide and you ask for us to make it 5000px, we will serve you the original 1000px image. Upscaled images are usually of poor quality and we want to avoid that.
• If your server takes longer than 10 seconds to upload the image to Photon, the upload will time out and your image will appear to be broken. Try to upload a differently-named image with a smaller file size if this happens.

Themes and plugins can also use the Photon API to transform images using GET query arguments. Developers will find Photon API examples and documentation on developer.wordpress.com.

Photon is only allowed to be used by sites hosted on WordPress.com, or on Jetpack-connected WordPress sites. If you move to another platform, or disconnect Jetpack from your site, please also switch to another magic image service. Abuse of Jetpack or violation of the WordPress.com Terms of Service could result in suspension of your site from WordPress.com-connected services.