- `ExportOptions.hdr` (`hdr` param): photos edited in HDR export as ISO
21496-1 gain map JPEGs (the SDR rendition as the base, the gain map measured
against it as written) or 32-bit float TIFF with highlights above 1.
Other formats and SDR edits export as before.
- Output sharpening and watermarks apply to both renditions.
- `develop.hdr {enabled?, maxEv?}` turns HDR editing on/off and sets the
headroom limit.
Checked on macOS: ImageIO reports both the ISO and the Apple gain map, and
CoreImage's HDR decode of a 3 EV edit reaches 2.95 EV.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
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