Apply automatic conversions to a resource. The auto parameter accepts the following options:

  1. optimize
  2. format


With auto=optimize set, we apply a best-effort techniques to to reduce the size of the resource. The quality setting is set to q=75 by default.

auto=format is respected, so images will be served in WebP format for browsers that support it.


Witn auto=format set, we will convert images to a better format. Using browser signals and image analysis, WebP capable browsers will be served WebP images, images that contain transparency will be served in PNG format. PNG images that appear to be photographs will be converted to JPEG images.