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Opened 11 months ago

Last modified 7 months ago

#58288 new defect (bug)

No support for JPG with HDR gain maps

Reported by: gregbenz's profile gregbenz Owned by:
Milestone: Awaiting Review Priority: normal
Severity: normal Version:
Component: Media Keywords:
Focuses: Cc:

Description

HDR ("high dynamic range") images offer vastly improved image quality on supporting hardware (see here for more details: ).

When displaying an HDR image on an SDR (standard dynamic range) screen, the image needs to be "tone mapped" to fit the reduced dynamic range of the screen. That can provide mediocre results, and a separate SDR version of the image will usually look better on an SDR monitor. Supplying two versions of the same image is complicated, and that is the reason for the new "gain map" proposal.

Adobe has published the gain map specification (and test images) at https://helpx.adobe.com/camera-raw/using/gain-map.html#resources and Chrome Canary v115 already supports proper rendering of the JPG gain map (be sure to view on a true HDR display, such as the M1 / M2 MacBook Pro).

JPG gain maps (with an SDR base image) offer an ideal way to support HDR as we all transition to HDR over time. They will display in an ideal way on both an SDR or an HDR display. And they will safely display as SDR in browsers which do not understand gain maps.

When a JPG with a gain map is uploaded to the WordPress media library, it is converted to an SDR JPG. The gain map is lost and therefore the image will no longer properly display as HDR when viewed on HDR hardware using a browser which supports HDR gain maps (such as Chrome).

Change History (2)

#1 @Presskopp
11 months ago

  • Component changed from General to Media

#2 @gregbenz
7 months ago

JPG HDR gain maps are now supported in Adobe software and most browsers. More info on how to create them: https://gregbenzphotography.com/hdr-images/jpg-hdr-gain-maps-in-adobe-camera-raw/#developers

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