This policy allows a document to serve images whose dimensions are larger than the container in which they are rendered on the page. Rendering images smaller than their native size is a waste of bandwidth and requires additional CPU. By default, this policy is allowed, and images may be oversized by an unlimited margin, but documents which are disallowed from doing this, will be allowed to oversize by up to a factor of 2. If this factor is exceeded by any image on the page, a placeholder image will be rendered instead.

How to apply this policy

Send the following HTTP header to control the oversized-images policy, and disallow it on all origins:

Feature-Policy: oversized-images 'none'

Does it work?

Currently Firefox, and Chromium based browsers, such as Google Chrome, Samsung Internet, and Opera, are the only user-agents to support Feature Policy. The minimum version that correctly recognises the oversized-images policy is:

Mozilla Firefox

Not supported

Google Chrome


Microsoft Edge

Not supported

Apple Safari

Not supported