iPhone HDR Gain Map Analyzer

Author: Daoyu Li (DaoyuLi@outlook.com)

About

This tool extracts HDR Gain Map images and ISO 21496-1 metadata from iPhone-captured HDR JPEG files. It also provides a GUI for interactive analysis, including:

• Extracting baseline, gain map, and metadata from a single iPhone HDR JPEG (iOS26 or later)
• Visualising the relationship between baseline luminance and gain values via scatter plots and histograms
• Interactively selecting luminance ranges to highlight corresponding regions in both baseline and gain map images

Only academic use is permitted. For commercial or corporate use, please contact the author first.

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Requirements

• Python 3.8+
• ExifTool (download from exiftool.org) – place the executable at ./tool/exiftool/exiftool.exe or modify the path in the code
• Python packages:
  • numpy
  • pillow
  • matplotlib

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Usage

python main.py

1. Click Open HDR Image and select an iPhone HDR JPEG.

2. Click Parse & Plot – the baseline image, gain map, and metadata will be loaded.

3. Use the luminance range input boxes (0–255) and press Confirm to highlight pixels within that range (others are darkened).

4. The scatter plot and histograms show the full data.

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License & Terms

• Open source for academic research only.

• Any commercial or corporate use must obtain prior written permission from the author.

• Redistribution, modification, or incorporation into proprietary products is not allowed without permission.