The HDR colour pipeline from set to post

A colour pipeline is the chain of transforms, files and displays that carries the camera image from the sensor to the final master. On a streaming production with HDR delivery, the pipeline has to work in two directions at once: it must show the director and producers an accurate preview of the final look on set and in editorial, and it must keep the original camera data untouched so finishing has the full range to work with. A broken pipeline is one of the most common causes of surprises in the grade, such as dailies that looked good but a master that looks different, or HDR highlights that nobody saw until finishing. This lesson explains how productions design an HDR pipeline, what role ACES and other colour-management systems play, how monitoring works on set and how looks travel from the DIT to the colourist.

Scene-referred and display-referred thinking

A useful way to think about a pipeline is to separate the scene from the display. Camera log and raw files are scene-referred: their values relate to light in the scene. A display needs display-referred values: brightness and colour for a particular kind of screen, such as SDR Rec. 709 at 100 nits or PQ HDR at 1,000 nits. The pipeline converts between them with transforms.

• Input transform: converts each camera's log or raw encoding into a common working space.
• Look: the creative adjustment, such as a show LUT or a set of grading decisions, applied in the working space.
• Output transform: converts the working space to a specific display, such as SDR Rec. 709 or HDR PQ at 1,000 nits in P3-D65.

When the look lives in the working space and output transforms are applied last, one creative look can drive both HDR and SDR monitoring. This is the key idea behind most modern HDR pipelines.

ACES and other colour-management systems

The Academy Color Encoding System (ACES) is an open framework, maintained by the Academy of Motion Picture Arts and Sciences, that defines working spaces, file formats and transforms for this kind of pipeline. Input transforms convert camera data into ACES, and output transforms render ACES to specific displays. ACES 2.0, released in 2025, introduced a new set of output transforms designed to handle HDR and SDR more consistently and to reduce problems with very saturated colours. Some productions use ACES; others use a camera manufacturer's wide-gamut working space or a grading application's own colour management, such as a wide-gamut intermediate in DaVinci Resolve. All of these follow the same scene-referred idea.

Whatever the choice, document it. Write down the working space, the input transforms for each camera, the look, the output transforms and the version numbers, and share the document with the DIT, dailies, editorial, VFX and the finishing facility.

The show LUT and the CDL

Most productions build a show LUT during camera tests: a transform, often designed by the DIT or colourist with the DP, that gives the intended starting look. On set, the DIT can make per-scene adjustments using an ASC Color Decision List (CDL), a simple and widely supported set of values: slope, offset and power for each channel, plus saturation.

Because CDL values are just numbers, they travel easily from the DIT's system into dailies, editorial and finishing. The colourist can load them as a starting point and see what the DP intended on set. For HDR, the CDL and the show look should be applied in the scene-referred working space, before the output transform, so they work for both HDR and SDR displays.

Monitoring HDR on set

Monitoring HDR on set is harder than in a grading suite. Sets are bright, monitors are often battery powered and far from the camera, and many people watch at once. Common approaches include:

• SDR monitoring for most of the crew, using the SDR output transform, with HDR monitoring for the DP, DIT and director at the DIT station.
• A calibrated HDR monitor in a shaded DIT tent or video village, able to reach at least the planned mastering peak for critical checks.
• HDR false colour or nit readouts on the DIT's scopes, so the DP can see where highlights and skin tones sit in nits.
• Regular checks of practical lights, windows, skies and specular highlights, which can look fine in SDR but jump out in HDR.

Many DPs light and expose mainly by SDR monitoring and waveforms, and use HDR checks to catch problems such as clipped practicals, distracting bright edges and noise in deep shadows. The goal is not to grade on set but to make sure the image will grade well.

Reference displays and viewing conditions

The final HDR grade is done on a reference display that can show the full mastering range accurately, such as a 1,000-nit P3-D65 monitor, in a room with controlled lighting. BT.2100 describes a reference viewing environment with a dim surround of about 5 nits. Streamers' mastering guidelines often require a display that reaches at least the mastering peak with a specified black level and calibration accuracy, and some list approved reference monitors. On set and in editorial, monitors are rarely that accurate, so the pipeline should account for differences:

• Calibrate all critical monitors regularly with a probe and record the results.
• Keep surround lighting dim and neutral when judging HDR, even on set.
• Avoid judging final colour on consumer televisions with motion smoothing, dynamic contrast or vivid modes turned on.
• Use the same output transforms on every critical monitor.

Colour accuracy is often described using delta E (ΔE). A common calibration target for reference monitors is an average ΔE well below 2 across test patches, because differences of about 1 to 2 are near the threshold of visibility. CINE-310 covered calibration in the grading suite.

Dailies and editorial

Dailies must carry the look reliably to producers, editors and the service. The DIT or lab applies the input transform, show look and CDLs, renders SDR viewing files for most people and HDR files where the service or director wants them, and keeps the original camera files untouched. Editorial works with proxy files that use the same look, so the director and editor get used to the intended image. Important habits:

• Embed or link CDL values to each clip in metadata, using standard formats.
• Keep metadata such as reel names, timecode, lens data and frame lines intact.
• Send the service's dailies team the formats it asks for, sometimes including HDR viewing copies.
• Report and log problems such as clipped highlights, flicker and dead pixels early, so they can be fixed or reshot.

When dailies, editorial and finishing all use the same documented pipeline, the colourist's first pass in the final grade looks like the dailies, and the session can focus on refinement rather than reconstruction.

Visual effects in the pipeline

Visual effects vendors need scene-referred plates and clear instructions about colour. Most productions send VFX plates in a linear or log working space such as ACES2065-1 in OpenEXR files, with the show LUT and CDLs as reference only. Finished shots come back in the same space, so the colourist can grade them like camera footage. Problems arise when a vendor bakes a look into a shot or uses a different transform version. A VFX colour document, shared at the start, prevents this.

The cinematographer's pipeline checklist

A short checklist helps the DP keep the pipeline under control.

• Choose and document the working space, transforms and versions with the DIT and colourist during prep.
• Build and test a show look for both SDR and HDR outputs, using footage from every camera and lens.
• Agree how HDR will be checked on set, who has the HDR monitor and how highlights will be measured.
• Make sure dailies, editorial and VFX use the same look and transforms.
• Review dailies in HDR periodically, not only in SDR.
• Carry the CDLs and look into the final grade and attend the grade where possible.