Runway Ruby Turns SDR Clips Into HDR Files

Ordinary video files are SDR. HDR is the wider brightness range used in finishing rooms, HDR TVs, and compositor pipelines. Releasebot's August 20, 2026 Runway API notes describe a new endpoint that takes an SDR clip and returns HDR without re-rendering the picture. Runway named the capability Ruby.

Runway's own post the next day said Ruby is on Max plans and Enterprise, and that it can "generate or convert any video into 16-bit EXR sequences or 10 and 12-bit ProRes and HEVC, in BT.2020 color with PQ or HLG." The API notes and the product tweet describe the same family of outputs. The notes are more specific about billing, limits, and how Gen-4.5 fits next to it.

"The conversion preserves the source's own pixels and audio: brightness is extended into HDR headroom with a bounded, color-preserving grade, and nothing is re-rendered."

That sentence is from the Releasebot write-up of the Runway API notes dated August 20, 2026. If you already like the clip, Ruby grades it into HDR headroom and wraps the delivery format. It does not generate a new picture.

Four output wrappers on /v1/video_to_hdr

The endpoint is /v1/video_to_hdr. The notes list these outputFormat values:

• hdr10 (default): 10-bit HEVC with HDR10 metadata and BT.2020 signaling.
• hlg: the HLG cousin of the same HEVC delivery.
• hdr_prores: a BT.2020 + PQ ProRes .mov mezzanine. proresProfile is 422, 422 HQ, or 4444, defaulting to 422 HQ.
• hdr_exr_sequence: a zip of half-float OpenEXR frames as linear BT.2020 light, plus colorimetry and provenance sidecars, and audio.wav when the source has audio.

Inputs have to be SDR. HDR-tagged videos are rejected. Clips are at most 40 seconds and under 4096 pixels per side. Those three constraints are in the same API note. A two-minute 6K master will not go through this call as-is.

Credits: 20 per second, 40 past 4K

Releasebot quotes the billing line as 20 credits per second, or 40 credits per second when the source is larger than 4 megapixels (roughly 4K). A 10-second 1080p conversion is 200 credits. The same length at over 4 megapixels is 400. There is no dollar figure in the note. Credits are plan currency. Max and Enterprise are the plans named in the X post; the API note does not publish a free-tier path for this endpoint.

A sibling note on the same day covers Gen-4.5 text-to-video and image-to-video delivering HDR directly via outputFormat values including hdr10, hlg, hdr_prores, and hdr_exr_sequence. Those are "true HDR renders — graded into BT.2020 with measured HDR10 metadata — not tone-mapped afterward," again from Releasebot. Non-mp4 formats add 5 credits per second for ProRes and PNG sequence, or 20 credits per second for 10-bit and deeper profiles including EXR, rising to 40 over 4 megapixels. Aleph 2.0 gets 10-bit SDR delivery; HDR for an Aleph edit is chained through /v1/video_to_hdr.

Two paths, then. Generate already in HDR from Gen-4.5. Or take any SDR clip, including an upload, and run Ruby. The second path is the one that matters if the footage did not come from Runway.

What a newcomer actually does

You need a Max or Enterprise Runway account, per the August 21 post, or an API key on an account that has the endpoint enabled. The notes say the Gen-4.5 HDR formats "are being enabled progressively per account," so a key that can generate 1080p SDR may not yet have Ruby. If the call 404s or rejects the format, that is the progressive rollout, not a wrong model id.

A minimal call shape from the published field names:

POST /v1/video_to_hdr
{
  "video": "<asset id or URL>",
  "outputFormat": "hdr_prores",
  "proresProfile": "422 HQ"
}

Pick hdr10 if you want a file you can play on an HDR TV. Pick hdr_prores if an editor is going to cut it. Pick hdr_exr_sequence if a compositor is going to grade it against other linear EXR. The zip is not a substitute for a movie file; it is a frame sequence plus audio on the side.

SDR in, HDR-tagged files rejected. Forty seconds, 4096 on the long side. If your export is longer, cut it first. If it is already HDR, Ruby will not take it. Those are the hard edges in the note, not folklore.

Where this sits next to a traditional grade

A colorist still does shot matching, look development, and delivery trims. Ruby's published job is narrower: extend brightness into HDR headroom with a bounded, color-preserving grade and wrap the result in a delivery format. The note is explicit that pixels are not re-rendered. Treat it as an automated first HDR pass plus a wrapper, not as a replacement for a finishing session on a feature.

For a beginner making short AI clips, the practical win is skipping a separate DaVinci project just to get a ProRes PQ file out of a 20-second generation. For a post house already on Max or Enterprise, the practical win is an API step that emits EXR the comp team already knows how to ingest. Both of those follow from the published formats. Neither requires believing a demo.