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The Content-DPR response header is used to confirm the image device to pixel ratio in requests where the screen DPR client hint was used to select an image resource.
| Header type | Response header, Client hint |
|---|---|
| Forbidden header name | no |
| CORS-safelisted response header | no |
If the DPR client hint is used to select an image the server must specify Content-DPR in the response. If the value in Content-DPR is different from the DPR value in the request (i.e. image DPR is not the same as screen DPR) then the client must use the Content-DPR for determining intrinsic image size and scaling the image.
If the Content-DPR header appears more than once in a message the last occurrence is used.
Note:
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Content-DPRwas removed from the client hints specification in draft-ietf-httpbis-client-hints-07. The Responsive Image Client Hints spec proposes to replace this header by specifying intrinsic resolution/dimensions in EXIF metadata.