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How do I create a shareable HDR image file, in either HEIC or AVIF format, from a RAW? The RAW format should have all the information necessary to create a real HDR image I think.

With real HDR I mean a picture that actually needs a HDR display to display properly, not the multi-exposure thing we've had for more than a decade.

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    \$\begingroup\$ What camera? What OS? What display? For Canon see here \$\endgroup\$
    – xenoid
    Jan 12, 2022 at 9:40
  • \$\begingroup\$ I'm pretty sure a 12- or 14-bit RAW file can already contain more data than a 10-bit HDR image… you just need a screen that can display it [P3 minimum, available on the newest Macs]. Note: Windows HDR is not "real HDR" [opinion redacted] & should be switched off. \$\endgroup\$
    – Tetsujin
    Jan 12, 2022 at 18:37
  • \$\begingroup\$ Yeah exactly, that's the whole point of my question @Tetsujin. I have RAWs (Pentax K20D PEFs/DNGs) that I want to convert to a sharable HEIC/AVIF HDR format. The file(s) should be viewable on all displays/OSs that support HDR and either be in the HEIC or AVIF formats for easy web embedding. \$\endgroup\$ Jan 16, 2022 at 7:16
  • \$\begingroup\$ Your Pentax can shoot at best Adobe RGB - which is already outside the gamut of most displays. If you want to export those at full 16-bit, then use TIFF. From tif, you can then attempt to save to HEIC - but HEIC still requires a profile. Converting to a profile you cannot see yourself makes little sense. HDR is not a single specification & is not 'display-ready' for most people. Windows' HDR is little but a guess & makes most things simply too punchy, rather than accurate. Even Apple's native P3 HEIC files are still only 8-bit. Also, many browsers have no idea what to do with HEIC P3 files. \$\endgroup\$
    – Tetsujin
    Jan 16, 2022 at 9:44
  • \$\begingroup\$ See video.stackexchange.com/questions/21676/… \$\endgroup\$
    – Tetsujin
    Jan 16, 2022 at 9:45

3 Answers 3

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The point of HDR is to display an image that exceeds the available dynamic range (of sensor, display, or both).

If you have a sensor that can record more than sixteen bits per channel on each pixel and more than five stops brightness range, you can record "HDR" images without need of software, but you'll still need to do the usual exposure blending to be able to display detail in the extreme highlight and shadow areas simultaneously unless your display can show the same number of shades.

In practice, 16 bits per channel is generally considered "enough" because your eye can't reliably distinguish more than 256 brightness differences between complete black and complete saturation of a given channel. A range of five stops (= brightest 32x the light as darkest) is the limitation; negative film (especially the last generation from the 1990s and early 2000s) could record detail over a range of seven to eight stops (128x to 256x), though this generally required darkroom manipulation to fit into the ~five stops of dynamic range of printing papers.

So, in order to record HDR (more than five stops of range) you'd need a sensor that has a wider range than the common ones -- and that's going to be expensive. Astronomical sensors may have this capability (I'm not sure, I have no firsthand experience with those). Or you can stick with the current method of exposure blending, either automatically in software inside the camera (which takes away your control) or by bracketing exposure manually or automatically and blending the exposures to preserve detail, ideally without looking cartoonish like some of the earlier HDR images did.

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  • \$\begingroup\$ In practice, 16 bits per channel is generally considered "enough" because your eye can't reliably distinguish more than 256 brightness differences between complete black and complete saturation of a given channel. - the amount of implications required to claim that is way past 11. There is no logical way to claim that human eye reliably distinguishes only 256 shades. \$\endgroup\$ Jan 2 at 15:12
  • \$\begingroup\$ So, in order to record HDR (more than five stops of range) you'd need a sensor that has a wider range than the common ones - by what definition of "range"? \$\endgroup\$ Jan 2 at 15:15
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You can process RAW images as HDR now using Adobe Camera RAW (ACR) as of v15. I've posted a tutorial at https://gregbenzphotography.com/photography-tips/acr-15-adds-high-dynamic-range-output/

As well as many examples and much more detailed information on displaying, editing, and sharing HDR images as AVIF or JXL at https://gregbenzphotography.com/hdr/

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HDR photos contain a brightness value, which has nothing to do with 10BIT or 14BIT. This only needs to be written in when shooting. New cameras, such as Canon R5, can convert from RAW to HDR

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