HDR Merge Master
HDR Merge Master is a free, open-source tool that uses Blender’s compositor to merge exposure-bracketed images in batches.
What HDR Merge Master is
HDR Merge Master is a free, open-source tool that uses Blender’s compositor to merge exposure-bracketed images in batches. It can save output as 32-bit OpenEXR or Radiance HDR and creates tonemapped JPG previews alongside the merged files. Users can add multiple input folders and include subfolders recursively. Alignment options include no alignment, Hugin pre-alignment, or MTB alignment, depending on the Blender version and selected mode. A headless command-line mode supports folder processing, JSON batch input, alignment choices, thread settings, and cleanup. Processing camera RAW files requires RawTherapee, and adjacent PP3 profiles are used automatically. The project documents optional workflows with Blender, RawTherapee, Hugin, Luminance HDR, and PTGui; an included script can replace JPG paths with EXR paths in a PTGui PTS project. The tool is intended for HDRI workflows that use JPG previews before substituting EXR files for final export. Blender 4.5 LTS and 5.1 LTS are actively tested; older versions use a legacy script with reduced features. HDR Merge Master does not remove ghosting, and the maker advises using a steady tripod.
Good
- Merges multiple folders and recursive subfolders.
- Outputs 32-bit OpenEXR or Radiance HDR.
- Offers several alignment options.
- Includes a headless command-line mode.
Watch out
- Does not remove ghosting.
- RAW processing requires RawTherapee.
- Older Blender versions use a reduced-feature legacy script.
Who it suits
HDR Merge Master may suit photographers building HDRI images from exposure brackets, especially those working with Blender or PTGui. Camera RAW workflows require RawTherapee.
Verdict
HDR Merge Master provides batch HDR merging with several output and alignment options. Its lack of ghost removal and RAW-processing dependency are important workflow considerations.
The facts
Each one read from HDR Merge Master's own pages, with the date it was checked.
What it does
- Alignment
- It offers no alignment, Hugin-based pre-alignment, or MTB alignment modes, with MTB as the default.checked 4 Oct 2026
- Automation
- A headless command-line mode supports batch files, folder input, recursive processing, alignment options, thread counts, and cleanup.checked 4 Oct 2026
- Batching
- The app supports multiple input folders, recursive processing, and batch lists that can be imported or exported as JSON.checked 4 Oct 2026
- Batch processing
- Users can add multiple input folders and optionally process subfolders recursively.checked 3 Oct 2026
- Blender versions
- Blender 4.5 LTS or 5.1 LTS are actively tested; older versions use a legacy script with reduced features.checked 3 Oct 2026
- Download
- The installation instructions direct users to download the latest GitHub release and run hdr_merge_master.exe.checked 4 Oct 2026
- HDRI workflow
- The maker says Poly Haven uses the tool to merge exposure bracket sequences for HDRI creation.checked 4 Oct 2026
- HDR output
- The output format can be 32-bit OpenEXR or Radiance HDR.checked 3 Oct 2026
- Integrations
- The project documents optional use of Blender, RawTherapee, Hugin, Luminance HDR, and PTGui workflows.checked 3 Oct 2026
- License
- The repository identifies its license as GPL-3.0.checked 4 Oct 2026
- Notable limit
- The tool does not perform ghost removal, and the README recommends using a steady tripod.checked 3 Oct 2026
- Notable limitation
- The tool does not remove ghosting, and the maker advises using a steady tripod when shooting.checked 4 Oct 2026
- Other integrations
- The workflow can use Hugin's align_image_stack for image alignment and includes a script to replace JPG paths with EXR paths in PTGui project files.checked 4 Oct 2026
- Output formats
- Merged output can be 32-bit OpenEXR or Radiance HDR, and the app also creates tonemapped JPG previews.checked 4 Oct 2026
- Preview files
- The tool creates tonemapped JPG previews alongside the merged HDR files.checked 3 Oct 2026
- PTGui workflow
- An included script can replace JPG paths with EXR paths in a PTGui PTS project.checked 3 Oct 2026
- Purpose
- HDR Merge Master uses Blender's compositor to merge exposure brackets in bulk into 32-bit EXR files.checked 4 Oct 2026
- RAW processing
- RAW input is supported when RawTherapee is installed and the RAW option is enabled.checked 4 Oct 2026
- Release downloads
- The project distributes downloadable builds through GitHub Releases.checked 3 Oct 2026
- Requirements
- The maker actively tests with Blender 4.5 LTS and Blender 5.1 LTS; older Blender versions use a legacy merge script with reduced features.checked 4 Oct 2026
- What it does
- HDR Merge Master uses Blender’s compositor to merge exposure brackets in bulk into 32-bit EXR files.checked 3 Oct 2026
- Who it is for
- The README describes the intended workflow as creating HDRIs for stitching, then swapping JPG previews for EXR files before final export.checked 3 Oct 2026
Where it runs
- Linux builds
- The release notes state that Linux release binaries were added.checked 4 Oct 2026
The company
- Maker
- The repository owner is Greg Zaal, whose GitHub profile lists South Africa.checked 3 Oct 2026
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