Why can two iPhone ProRAW shots show different HDR headroom in Lightroom?
Asked 11/9/2025
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2 answers
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I shot the same scene a couple of seconds apart on an iPhone 16 Pro in ProRAW. In Lightroom, the two files look very similar with HDR editing off, but once HDR mode is enabled one file shows extra highlight headroom while the other does not.
No camera settings were intentionally changed between shots. The main differences I noticed were slightly different framing and that one frame was ISO 64 while the other was ISO 100. Why would two near-identical ProRAW images behave differently only in HDR editing mode?
Originally by Will Vousden. Source · Licensed CC BY-SA 4.0
Will Vousden
7mo ago
2 Answers
6
Your histograms look "similar", but a closer comparison shows that the second shot is exposed noticeably brighter than the first. Compare the positions of the "peaks" near the middle of each of the first two histograms to the symbols directly above them. Also compare the width and right side slope of the "peaks" near the right hand edge. The first image has no clipping in the highlights. The second image does have some highlight clipping. Notice how much thinner the large blue "peak" is and how much steeper the slope of its right side is.
The differences are more noticeable if one superimposes the two images and switches back and forth:
Please keep in mind that the histograms you see are based on the JPEG (or JPEG like) representations of the image you are currently seeing on your screen. It is not based on the total contents of the raw file.
These differences are enough to make the "automatic" processing algorithm treat the first image as if no overexposed highlights need to be recovered and to treat the second image as if there are blown highlights which need to be recovered.
Originally by Michael C. Source · Licensed CC BY-SA 4.0
Michael C
7mo ago
0
Generated from our catalog & community — verify before relying on it.
The most likely reason is that the files were not actually captured identically in the highlights.
From the histograms, one frame appears a bit brighter and shows some highlight clipping, while the other retains more highlight detail. With HDR editing off, Lightroom is showing a more compressed rendering, so the two files can look similar. When HDR mode is enabled, any extra highlight data/headroom becomes visible, so the difference between the captures is much more obvious.
On iPhone, even ProRAW is not a completely untouched raw workflow. The phone still applies computational processing/tone mapping, and that can vary from shot to shot even a few seconds apart. Slight framing changes can also affect how the phone decides to process the scene.
So the mismatch is likely a combination of:
- one shot being exposed a little brighter and clipping highlights more
- Apple’s scene-dependent computational processing changing between frames
If you want more consistent results, reduce the phone’s automated look as much as possible (for example, flatter rendering / less Smart HDR-style processing where available).
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UniqueBot
AI7mo ago
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