Links, papers, discussion threads, example images and libraries related to HDR using gain mapped JPEGs. This repository started as a collection of links and papers about color HDR. Then after CIC32 it accumulated applications and images from a parallel 30 day challenge on gain maps. Now it's a combination of these threads, a work in progress and a range of samples including photography, video games, visualization and test targets.
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There is also a multi-page Streamlit app (that includes an HDR color picker) available for in-person demonstration. A SDR (ie non-gain mapped) screenshot jpg of this application is below. For comparison, a gain mapped version of this astronomy image is here :
The resulting gain mapped JPGs have been validated using a MacBook Pro M3 (Sonoma 14.6.1) display and the Brave Browser (1.76.73). The Streamlit dark mode is used for the demo app and a comparable viewing condition may be preferred when viewing the example gain mapped jpegs.
- HDR Gain Map Analyzer : A concise tool that decodes HDR Gain Map images and ISO 21496-1 metadata from dual-layer HDR JPEGs. Supports single-channel and three-channel gain maps. Pure-Python — no ExifTool required.
- by daoyuli
- r/Lightroom : I got tired of my HDR edits dying after export, so I built a free/open-source Mac app to fix it
- HDRify : Read/write HDR, EXR and UltraHDR JPGs (Gain maps), includes tone mapping and color space support.
- Online tool by bhouston
- repo includes /assets with examples
- HDR Flashbang : Make an image extremely bright - by Riley Walz
- HDR Image Generation via Gain Map Decomposed Diffusion : (ICCV 2025)
- Convert HDR files to Gain Map HDR : A tool to convert HDR file to Adaptive HDR (Gain Map HDR) and ISO HDR format in HEIC
- HDR2gainmap : RAW photo development to HDR with gain maps, tuned for accurate rendering in Apple Photos
- HLG to SDR/HDR : macOS app for camera HLG HEIF stills (Sony
.HIF, Nikon Z). Folds them to SDR with a choice of operator including BT.2446 Method A, or writes JPG / HEIC carrying an ISO 21496-1 gain map. Installs a Photos editing extension, so the conversion runs on the HLG master rather than on an already folded export. Free.- by dmitry907
- repo page includes side by side comparisons measured against the original HLG file
- Gain-MLP: Improving HDR Gain Map Encoding via a Lightweight MLP
- T. Canham, S. Tedla, M.J. Murdoch, M.S. Brown - March 2025
- "The proposed MLP network architecture. Given the SDR image’s pixel coordinates and RGB values, the network encodes each pixel in a 120-element sine embedding, which is then passed to a two-layer MLP, whose weights are optimized to predict the corresponding gain or gamma map values at each pixel."
- ISO HDR Images Test Sets (22028-5, 21496-1)
- These free images test sets are licensed under the CC BY-NC 4.0 license.
- 1 - ISO_22028-5_HDR_PQ_4.93 : contains 24 ISO TS 22028-5 PQ images, with up to 4.93x headroom
- 2 - ISO_21496-1_Adaptive_HDR_4.93 : contains 24 Adaptive HDR images, with up to 4.93x headroom
- 3 - ISO_22028-5_HDR_PQ_Metadata : contains 23 ISO TS 22028-5 PQ images, with no headroom constraints, and with appropriate metadata
- 4 - ISO_21496-1_Adaptive_HDR : contains 23 Adaptive HDR images, with no headroom constraints
- How to work with HEIC image file types in Python
- pillow-heif : Python library for working with HEIF images and plugin for Pillow.
- ISO/TS 22028-5:2023(en) : Photography and graphic technology — Extended colour encodings for digital image storage, manipulation and interchange — Part 5: High dynamic range and wide colour gamut encoding for still images (HDR/WCG)
- Proposal: gain maps for PNG #380
- ICC HDR Stills Expert Day : 2024
- DCI-P3 : DCI-P3 is a color space defined in 2005 as part of the Digital Cinema Initiative, for use in theatrical digital motion picture distribution[1] (DCDM[2]). Display P3 is a variant developed by Apple Inc. for wide-gamut displays.
- Other Awesome lists
- Paper List | High Dynamic Range Imaging : lists many papers and recent models
- Awesome-Deep-HDR : A collection of deep learning based methods for HDR image synthesis
- ICtCp color space : Dolby
- ICtCp : a color representation format specified in the Rec. ITU-R BT.2100 standard that is used as a part of the color image pipeline in video and digital photography systems for high dynamic range (HDR) and wide color gamut (WCG) imagery.[1] It was developed by Dolby Laboratories[2] from the IPT color space by Ebner and Fairchild.
- ICtCp - Dolby Whitepaper
- Rec. 2020
- Rec. 2100
- CIC 2018 Paper : Assessing Color Discernibility in HDR Imaging using Adaptation Hulls
- SMPTE 2017 Conference : Hitting the Mark - A New Color Difference Metric for HDR and WCG Imagery
- Coding-independent code points : a way to signal the properties of a video or audio stream.[1][2] It can describe the color profile of videos (and still images) in a simpler way than the use of ICC profiles.[3]
- EI 2023 Plenary 2: Embedded Gain Maps for Adaptive Display of High Dynamic Range Images
- More papers
- Advanced High Dynamic Range Imaging by Francesco Banterle, Alessandro Artusi, Kurt DeBattista (2021)
- HDR_Toolbox : HDR Toolbox for processing High Dynamic Range (HDR) images into MATLAB and Octave
- GNU Octave : The Octave syntax is largely compatible with Matlab. The Octave interpreter can be run in GUI mode, as a console, or invoked as part of a shell script.
- Francesco Banterle : Home Page and on github
- PICCANTE : High Dynamic Range (HDR) Library
- Dolby Vision to HDR10, SDR, and HLG Video Converter
- HDRutils : Some utility functions to generate HDR images from a sequence of exposure time or gain modulated images
- HDR 10
- HDR10, is an open high-dynamic-range video (HDR) standard announced in 2015
- HDR 10+
- Ultra HDR Image Format v1.1
- SkJpegGainmapEncoder.cpp
- ISO 21496-1 gainmap support
- SkAndroidCodec: Add gainmap image decoding support
- google/libultrahdr
- imagecodecs library for image format decode / encode, including libultrahdr (1.3.0)
- Playing around with Ultra HDR and ths code, also uses ffmpeg
- I know PNG can handle and contain HD colors, but can it contain HDR colors?
- rawpy : an easy-to-use Python wrapper for the LibRaw library.
- AppleJPEGGainMap : Generating JPG + Gain Map HDR Photos Compatible with iPhones/Macs Photos
- Gain Maps by Eric Chan at Adobe
- Gain Map : Adobe
- Mac Demo App and corresponding documentation
- Gain Map Sample Photos
- JPEG-XL
- ACES
- Applying Apple HDR effect to your photos : You can decode and apply Apple’s HDR gain map to your own images.
- Gain Map - discussion thread
- High Dynamic Range color grading and display in Frostbite : slides
- The high dynamic range imaging pipeline: Tone-mapping, distribution, and single-exposure reconstruction, by Gabriel Eilertsen (2018)
- ColorAide : A library to aid in using colors . . . about ICtCp
- Greg Benz Photography : HDR JPG Gain Map Gallery
- Use Brave browser to view JPEGs with gain maps
- gainmap-js : A Javascript (TypeScript) Encoder/Decoder Implementation of Adobe's Gain Map Technology for storing HDR Images using an SDR Image + a "Gain map"
- How to convert JPG images to AVIF with Python
- darktable : an open source photography workflow application and raw developer.
- Extensible Metadata Platform - XMP : save specific sequence of image edits
- OpenEXR : Test Images
- NEF Format : Nikon Electronic Format (NEF)
- pixls.us : Play Raw category . . . such as
- CR2 : Canon Raw v2 (CR2) . . . Canon 5D camera
- ISET/isetcam . . . (notes w Octave?)
- A most unusual brightness : "The illustrations for Digital Divinity make use of this effect in a brilliant (literally) way by masking a pure white, HDR video such that parts of the illustration glow with an ethereal brightness."
- Inverse Tone Mapping - Upscaling SDR Content to HDR
- Welcome to the wide-gamut test page
- dtinth/superwhite
- "display a very bright white color on HDR-enabled displays with ~1 KB of video file"
- it really is quite bright
- Perceptually uniform color space for image signals including high dynamic range and wide gamut
- Visualizing Errors in Rendered High Dynamic Range Images
- HDR Merge : "Get increased dynamic range in your photos by merging your bracketed RAW files directly within Capture One. The result is a linear DNG that behaves like a RAW file for further editing."
- Color Grading & Finishing : How to - Add a LUT in Avid Media Composer
- Exposure Fusion – local tonemapping for real-time rendering
- HDR NITS ARE A LIE: IT’S TIME TO EMBRACE THE STOP
- Adventures in EDR, Part 1: Displaying EDR Photos in iOS 17 and Adventures in EDR, Part 2: Metal
- How Could I extract MPF images (HDR gain Map) from iPhone's jpegs?
- brew install exiftool
exiftool -b -MPImage2 image_w_gain_map.jpg > gain_map.jpg- Using ExifTool to modify metadata
- OpenCV : High Dynamic Range Imaging : tonemapped and with exposure fusion
- Reading/writing JPEG MPF (Multi-Picture Format) files
- High Dynamic Range Imaging - Exposure sequence & Exposure fusion - EXPOSURE FUSION
- Manual creation of UltraHDR images : discussion thread
- Day-to-Night Image Synthesis for Training Nighttime Neural ISPs : CVPR'22 Oral
- HEIC Image Processing Tools - heic-shenanigans
- Computationally Efficient HDR Video Using a Packed Video Gain Map : Technical Disclosure Commons (2024)
- Use HDR for dynamic image experiences in your app : Apple Developers Video, WWDC 2024
- Gamma Maps: Non-linear Gain Maps for HDR Reconstruction
- Improving-Color-Space-Conversion-for-Camera-Captured-Images-via-Wide-Gamut-Metadata
- Monochrome vs Color Gain Map Examples : from the website of Eric Chan
- American Science & Surplus is fighting for its life. Here’s why you should care. - neat place, nice gain mapped photos
- The iPhone 15 Pro's Depth Maps : and the gain maps
- Apple/Adobe の Gain Map HDR について調べて軽く実装をしてみた
- Process Apple Gain Map: The ImageIO & the Core Image approaches
- Adventures in EDR, Part 1: Displaying EDR Photos in iOS 17 : "Video of the Photos app showing a photo of a sunset, with the sun getting brighter as EDR kicks in."
- vincenttsang/HDR-Gain-Map-Convert : 基于SwiftUI编写的PQ_HDR_to_Gain_Map_HDR转换工具的HDR图片转换器GUI界面
- A Subjective Comparison of Three Standard Tone Mapping Algorithms for HDR-to-SDR Conversion
- Learning Gain Map for Inverse Tone Mapping - ICLR2025
Procedurally generated gain mapped jpeg : motivated by #genuary