HDR photos from any RAW file
14 October, 2023 - Categories: Photography - Tags: HDR
HDR Displays are becoming more widespread, but HDR photos are quite rare in photography. In this article, we are going to see how to use Darktable to produce an HDR image file (JPEG XL) from a RAW file.
HDR or High Dynamic Range is a misleading term in photography, usually referred to the technique of shooting multiple photos with different exposures to capture the full dynamic range of an high contrast scene.
In the recent years we saw the rise of HDR as a standard for TVs, screens and files. We are going to talk about HDR files, not the technique.
HDR is slowly permeating as a technology. Most mid to high-end TVs support it, Most iPhones, iPads and Macbooks support it. Recent mirrorless cameras are also starting to produce HDR images (like the 2021 Sony A7 IV) in the form of 10-bit HEIF files.
I began wondering if I could produce HDR files from my 2015 Sony A7R II, with its 14-bit Dynamic Range sensor. I decided to use Darktable as it's free software and does not require purchase or subscription.
After several months of failed attempts I was able to produce an HDR file, these are the steps:
Steps
- Install Darktable
- Preferences/Processing/auto-apply pixel workflow defaults: scene-referred (sigmoid)
- Double click a photo to switch to the Darktable tab
- From the Correct tab on the right: Enable Lens Correction module
- From the Color tab: Color balance rgb, right click and select basic colorfulness: standard or natural skin
- From the Active modules tab: Select HLG Rec2020 RGB
- On the Export panel: file format: JPEG XL; bit depth: 10bit
- Open the Export preferences: tick all the boxes (it's necessary to include metadata in the output file)
- Click export
This will provide you with an HDR photo in JPEG-XL format. The HLG color space is capable of displaying the photo also on SDR screens.
Unfortunately, the Darktable workflow is not designed yet with HDR in mind, so you won't get any instruments to help you modify the photo luminance, example: Lightroom HDR output.
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