How to merge bracketed exposures into HDR
Merge to HDR in Paint by Zaweba aligns bracketed shots, removes ghosts and gives a tone-mapped result or a 32-bit radiance map as .hdr or .exr.
Choose File > Automate > Merge to HDR and pick your bracketed shots. Paint by Zaweba lines them up, removes ghosts left by anything that moved between frames, and gives you either a tone-mapped picture ready to edit or a 32-bit radiance map that keeps the full range of light. The radiance map can be saved as .hdr or .exr.
Bracketing means taking the same scene at several exposures, usually one dark, one normal and one bright. Each frame captures part of the range: the dark one holds the bright sky, the bright one shows into the shadows. Merging them gives one picture with detail in both, something a single shot can't hold in a high contrast scene like a sunset or a room with a window.
What you need
Two or more photos of the same scene at different exposures, ideally three or more one or two stops apart. A tripod helps but isn't essential, since the merge aligns the frames. RAW files or high quality JPEGs both work. Paint by Zaweba is free and offline on Windows.
Step by step
Choose File > Automate > Merge to HDR and select the bracketed photos. Paint aligns them, so small movements of the camera between frames are corrected.
If anything moved between frames, such as leaves, water, clouds or people, ghost removal deals with it, so you don't get see-through doubles.
Then choose what you want back. A tone-mapped result squeezes the full range into a normal picture you can edit and export straight away. A 32-bit radiance map keeps every value as captured, including brightness far beyond what a screen shows, for use in 3D lighting, compositing, or for tone mapping yourself later.
Tone mapping it yourself
If you kept the 32-bit result, Paint by Zaweba opens it as a 32-bit document in linear light. You can then use HDR Toning, which offers local adaptation with edge glow radius and strength, exposure, gamma, highlight compression, shadow and highlight, vibrance, saturation and a toning curve. Shadows/Highlights is a gentler alternative. When converting down to 8-bit for export, Paint dithers the result to avoid banding.
Getting a good result
Keep it natural unless you want a stylised look. HDR is famous for halos and grey, flat skies when pushed too far. Keep edge glow modest and look at the edges of buildings and trees against the sky, where halos appear first.
Shadows should still be darker than highlights. A picture where everything is the same brightness looks unreal. Leave some true darks and some bright points.
Shoot with fixed white balance and focus across the bracket, so frames only differ in exposure.
When to use the other modes
For scenes where there's no movement and you only need a little more range, a single RAW file developed with highlight and shadow recovery may be enough, and quicker. Paint's RAW Developer has those controls. For real high contrast scenes, Merge to HDR is the right tool.
Related automations
The same Automate menu has Panorama for stitching, Image Stacking for statistics such as mean or median across many frames, and Astrophotography Stacking with bias, dark and flat masters. A median stack of several frames is a neat way to remove passing people from a busy scene. Paint by Zaweba puts all of these in one place, with no account and no upload.
