MakeHDR

MakeHDR is an OpenFX plug-in for merging multiple LDR images into a single HDRI.

Feature Notes

• Merge up to 16 inputs with 8, 10 or 12 bit depth processing
• User-friendly logarithmic tone-mapping controls
• Advanced controls such as sampling rate and smoothness

Available cross‑platform on Linux, macOS, and Windows; works consistently in compositing applications such as Nuke, Fusion, and Natron.

Installation

Download the latest release and copy the MakeHDR.ofx.bundle directory to your custom OFX_PLUGIN_PATH or your system's default OpenFX plugin folder:

• Linux: /usr/OFX/Plugins
• macOS: /Library/OFX/Plugins
• Windows: C:\Program Files\Common Files\OFX\Plugins

How to Use

1. Create a MakeHDR node within your DCC app.
2. Connect your source images, shot with multiple shutter speeds.
3. Fill in the exposure times in seconds for the appropriate inputs (e.g., for a 1/250 shutter speed, enter 0.004).

Build from Source

If you prefer to compile the plugin yourself, ensure you have CMake ≥ 3.5 and a C++14-compatible compiler ready on your system. Then run:

git clone --recursive https://github.com/sosoyan/make-hdr.git
cd make-hdr && mkdir build && cd build
cmake .. && sudo make install

Parameter Reference

Exposure Times

Parameter	Description
calibrate response	Estimates the non-linear response curve from the source images. When disabled, assumes the source images are already linear.
1–16	Defines the exposure time in seconds for each corresponding connected image source.

Tone Mapping

Parameter	Description
target middle gray	Automatically adjusts global exposure so the average scene luminance matches the middle gray value.
middle gray	Defines a reference gray from the scene (e.g., sampled from a colour checker) to scale the merged image's luminance.
exposure	Applies a global exposure adjustment in stops to the merged HDR image before tone mapping.
gamma	Applies a gamma exponent per-pixel after HDR merging, where 1.0 keeps linear output.
highlights	Blends between fully compressed (0) and uncompressed linear (1) output. Lower values roll off bright areas more aggressively.

Advanced

Parameter	Description
show samples	Displays the sample positions on the output image as bright green pixels.
samples	Defines the number of calibration samples. For Debevec, it specifies the exact number of points. For Robertson, the value is multiplied by 100 to compensate for sparse bin coverage.
solver	Debevec solves a linear system (fast, sparse samples). Robertson uses an iterative expectation-maximisation approach.
smoothness / iterations	For Debevec, higher values force a smoother response curve. For Robertson, it sets the maximum number of expectation-maximisation iterations.
input depth	Determines the internal histogram resolution (256, 1024, or 4096 bins). Match this to your camera's original bit depth.
log level	Controls plugin logging verbosity. off silences all logging, while debug prints detailed per-frame diagnostics.