AI Video HDR Workflow: From 8-Bit Generation to a Graded HDR Master

Most AI video is delivered as an 8-bit H.264 file. That is fine for a social post. It is not fine for a colour grade, a broadcast master or an HDR deliverable. The moment a colourist pushes contrast or pulls a window on an 8-bit sky, the gradients band and the shadows fall apart.

We run an AI-native cinematic studio out of Sydney and we deliver to broadcasters, streamers and OOH networks across Australia. This is the workflow we use to take a fragile 8-bit generation to a master that a QC operator signs off without a second look.

What the tools actually give you

As of August 2026, only two generation models write high bit depth at the point of generation.

Luma Ray 3.2 outputs 10, 12 and 16-bit HDR as ACES2065-1 EXR frames, but only for 5-second clips at 720p or 1080p. LTX-2.5, the open-weights model from Lightricks, generates native 4K HDR and writes scene-linear 16-bit EXR.

Everything else is a consumer container. Runway Gen-4.5 generates at 720p SDR; its ProRes option is a wrapper, not a bit-depth upgrade. Google Veo 3.1 is 8-bit SDR with an AI upscale to 4K. ByteDance Seedance 2.5 is the strongest of the group at native 4K and 10-bit, but there is no HDR transfer function, no log and no EXR from ByteDance’s own channels. Kling 3.0 is native 4K at up to 60 fps, and the “16-bit HDR” claims you will see on reseller pages do not appear in Kuaishou’s documentation. We treat it as SDR until they say otherwise.

The practical rule: banding is set at generation. No enhancement recovers tonal steps that were never encoded.

The Apostle finishing pipeline

1. Generate at the ceiling. We pick the source per shot. Ray 3.2 HDR plus EXR when the shot is short and the latitude matters. LTX-2.5 when we want 4K HDR and a longer clip. Seedance 2.5 4K 10-bit for motion and reference control. We re-roll takes rather than rescue a broken 8-bit clip in the grade. The 3:1 pre-production-to-generation ratio applies here as much as anywhere.

2. Clean, then uplift. Starlight Precise 2.5 cleans compression artefacts and upscales. Then Topaz Hyperion 2.5 converts the 8-bit Rec.709 SDR to 10-bit ProRes in BT.2020 PQ, or to 16-bit half-float EXR in ACES2065-1. Hyperion is inverse tone mapping, not upscaling; it reconstructs highlight and shadow structure and expands bit depth. It is per-frame and it is aggressive. We dial it back, split scenes at every hard cut, and deinterlace first.

3. Colour-manage in Resolve. ACES with ACEScct as the working space, or DaVinci Wide Gamut with DaVinci Intermediate. HDR deliverables get a Rec.2100 PQ or HLG timeline from the start, not a conversion at the end.

4. Grade with a cinematographer’s eye. Reconstructed HDR reads as an automated “punchy” preset until someone makes decisions about skin, contrast and highlight roll-off. That is the DOP work, and it is the part no tool does.

5. Trim passes and mastering. For streaming, Dolby Vision L1 analysis on every shot and an SDR Rec.709 trim. Then one graded master goes out as ProRes 422 HQ for Free TV, ProRes 4444 XQ plus a Dolby Vision XML for Netflix-style delivery, and HEVC Main10 with Rec.2020 primaries and PQ or HLG transfer tags for YouTube HDR.

Where it breaks

Dark, muddy generations have too little range to build on. Blown highlights have nothing to reconstruct. Shots with inconsistent lighting make Hyperion bloom and surge. In every one of those cases the fix is upstream: a better generation, not a harder grade. We budget for that.

What “grade-ready” means at Apostle

A 10-bit ProRes or 16-bit EXR source, in a documented colour space, with enough tonal information that a colourist can relight, push secondaries and master to HDR without banding. Anything less is a preview, and we say so.

We deliver this from Sydney to clients in Melbourne, Brisbane, Perth, Adelaide, Canberra and everywhere in between, and we can walk your post team through the settings if you would rather finish in-house.

Talk to Apostle about an HDR finish for your AI campaign