How to use it
- Drop in .hdr files.
- Set the exposure, then the JPG quality.
- Download the previews.
Previews for an HDRI collection
HDRI environment maps are often 50 MB or more, and nothing but 3D software can show them. If you keep a library of them, or share them with a team, lightweight JPG previews make them browsable. An equirectangular HDRI converts to a wide 2:1 panorama JPG that shows the whole environment at a glance.
Exposure
Outdoor HDRIs contain a very bright sun and sky alongside much darker ground. The default exposure with filmic tone mapping usually gives a balanced view; drop the exposure by one or two stops if the sky looks washed out, or raise it for dim interiors. The same exposure can be applied to a whole batch, which keeps a library consistent.
Making them smaller
For thumbnails, run the JPGs through the resizer down to around 800 pixels wide; for a quick look, that is plenty.
HDR and JPG compared
| HDR | JPG | |
|---|---|---|
| First released | Late 1980s | 1992 |
| Compression | RGBE with simple run-length encoding | Lossy |
| Transparency | No | No |
| Animation or pages | No | No |
| Best for | HDR lighting and environment maps | Photos for sharing, email and print |
| Support | 3D software; needs tone mapping to view | Universal |
Questions people ask
Why does my HDR look too bright or dark?
HDR files hold more brightness than a JPG can. Adjust the exposure slider to choose which part to show.
Is the panorama shape kept?
Yes. Equirectangular maps stay 2:1.
Can I convert EXR files?
Not yet; only Radiance .hdr files.