Without regenerating the shot, Runway Ruby converts SDR video to HDR

Ruby converts up to 40 seconds of SDR video to HDR10, HLG, ProRes, or EXR. Gen-4.5 can also generate several native HDR formats.

SDR video can now be converted to HDR directly through Runway’s API without being processed again by a model that recreates its content. Called Ruby, the new tool expands the source file’s luminance and delivers several formats intended for broadcast, editing, color grading, and compositing.

Ruby is available through the `/v1/videotohdr` endpoint under the model name `ruby`. It can process an uploaded video, a Runway generation, or a result produced by an external model, provided the source remains in SDR.

Unlike a video generator or some enhancement tools, Ruby does not recalculate the content of the shot. Runway says the original image and audio track are preserved. The process applies a bounded, color-preserving grade that extends brightness into the available HDR headroom without replacing faces, textures, or other elements in the scene.

This approach reduces the risk of visual drift but cannot recreate information missing from the source. A clipped highlight, crushed shadow, or already damaged gradient will not automatically recover its original detail. The conversion redistributes the available values within an HDR signal; it does not return to the original capture or render.

Runway’s use of the term “true HDR” primarily describes the technical properties of the delivered files. Outputs use the BT.2020 color space, PQ or HLG transfer functions, and measured metadata for HDR10. This does not mean an SDR source retroactively gains the range of content originally captured or rendered in HDR.

HDR10 is the default output format. Ruby returns an MP4 file using HEVC Main 10, encoded in BT.2020 with a PQ transfer function. A second option produces HLG, also using 10-bit HEVC and BT.2020. HDR10 is commonly used for compatible displays and streaming platforms, while HLG remains widely used in broadcast workflows.

For editing and color grading, the `hdrprores` option delivers a BT.2020 PQ MOV file. Three profiles are available: ProRes 422, 422 HQ, and 4444, with 422 HQ selected by default. This output serves as an intermediate file better suited to exchanges between production tools than a compressed MP4 intended primarily for playback.

The most flexible format for compositing is `hdrexrsequence`. Each frame is stored as a half-float OpenEXR file, with the signal represented as linear BT.2020 light and a value of 1 corresponding to 100 nits. The files are packaged in a ZIP archive that also includes colorimetry and provenance sidecars. When the source contains audio, it is delivered separately as `audio.wav`.

The reference to output reaching 16-bit therefore applies specifically to half-float EXR sequences. It does not apply uniformly to HDR10, HLG, or the different ProRes profiles. The first two are delivered in 10-bit HEVC, while the documentation treats ProRes and EXR as separate output categories.

Ruby does not increase video resolution. It is a dynamic-range and color conversion tool, not an upscaler. Runway may only reduce the dimensions slightly so that they correspond to a multiple of 16, a technical constraint to consider when the framing or final dimensions must be preserved exactly.

There is a discrepancy between the announcement posted on X and the technical documentation. The announcement refers to videos lasting up to 30 seconds, while the current documentation allows SDR sources up to 40 seconds. The width and height must each remain below 4,096. Files already identified as HDR are rejected to prevent a second conversion.

Local files can be submitted through the API’s ephemeral upload system. It accepts files up to 200 MB and returns a `runway://` address that remains valid for 24 hours. The same address can be reused across multiple requests until it expires.

Conversion costs 20 credits per second, equivalent to $0.20 at the developer portal rate of $0.01 per credit. The price doubles to 40 credits per second when the source exceeds approximately four million image samples per frame, which includes most 4K files.

A ten-second conversion therefore costs $2 at the first tier or $4 for a source above that threshold. At the documented maximum duration of 40 seconds, the cost reaches $8 or $16, respectively. Billing is based on the output duration and the source file’s dimensions.

API credits are separate from those included with Runway app subscriptions. Ruby is therefore aimed primarily at teams and services capable of integrating the endpoint into a processing pipeline, rather than users looking for a one-off conversion directly within the consumer interface.

Runway is also adding professional and HDR output formats to Gen-4.5. The distinction from Ruby matters: Gen-4.5 can generate its result directly in HDR, while Ruby converts an existing SDR video after the fact.

Gen-4.5 now supports HDR10, HLG, 10-bit Rec.709 SDR, HDR ProRes, 16-bit HDR PNG sequences, half-float EXR sequences, and a lossless 12-bit PQ master. Runway says these HDR renders are produced directly in BT.2020 rather than converted after generation.

Aleph 2.0 gains 10-bit Rec.709 SDR and several editorial formats, but not native HDR rendering. A video edited with Aleph must therefore be sent through Ruby afterward to obtain an HDR version.

These formats carry a surcharge on top of the model’s initial price. Standard ProRes and PNG sequences add 5 credits per second. The 10-bit and HDR profiles add 20 credits per second, or 40 credits when the output exceeds approximately four million image samples per frame. This surcharge is added, for example, to Gen-4.5’s base rate of 12 credits per second.

Availability is being enabled progressively across accounts. Runway has not yet published an independent comparison between Ruby and the color-grading or HDR conversion tools already used in post-production. Color fidelity, temporal stability, highlight handling, and delivery compliance will therefore need to be checked on a calibrated HDR display using standard measurement tools.

Ruby does not automatically turn an SDR source into a