Short answer
A broadcast-legal picture keeps its red, green and blue components, and its luminance, inside the signal range the broadcaster accepts. Television does not use every code value in a file: black and white sit inside the scale with room above and below, and a programme that strays too far outside is rejected by automated quality control. The EBU's recommendation R 103 gives the ranges, the way to measure them, and a tolerance, because small excursions are unavoidable and harmless.
In a 10-bit broadcast signal nominal black is code 64 and nominal white is code 940, out of a scale that runs to 1,023. The EBU explains why the margins exist. In live production signals stray outside the nominal range for short periods, when a camera moves or the sun comes out, and if they were clipped hard the filters that process video would ring, leaving visible artefacts that every later stage would make worse. The headroom absorbs those excursions. The lowest and highest codes are also reserved by the interface itself and are never picture.
Video is usually carried not as red, green and blue but as a brightness signal and two colour-difference signals. That form can describe combinations that correspond to no real mixture of the primaries: turned back into red, green and blue, one component comes out below zero or above full. The EBU calls these illegal combinations. They arise from grading in colour-difference form, from sharpening and scaling overshoots, from graphics, and from converting a wider gamut into BT.709. A very saturated, very bright colour is the typical offender, as is a saturated colour that is very dark.
R 103 accepts that slightly out-of-range signals are hard to avoid. It sets a preferred range a little wider than the nominal one, which at 10 bits runs from 20 to 984, and calls anything beyond it a gamut error. It recommends filtering the signal before measuring so that single-pixel transients and noise are not counted, and says equipment should flag an error only when it covers more than one per cent of the picture. For graded, pre-produced material it asks that the nominal limits be followed closely; the wider tolerance is aimed at live work.
A legaliser is a processor that forces every pixel into range. The EBU advises caution: such devices may create artefacts more disturbing than the errors they remove, and should not be applied before all other processing is finished, since anything done afterwards can push the signal out again. A hard clip on one channel changes hue, and a clip on a gradient makes a visible edge. The better practice is to find the shots that fail, reduce the saturation or level of the offending colours in the grade, and keep the legaliser as a safety net.
The 2020 revision of R 103 was written because SDR and HDR programmes now travel in the same digital container. It notes that when HDR material is converted to SDR, some colours are expected to land outside the nominal BT.709 volume but inside the preferred range, and that the tolerance lets converters keep the brightness and saturation of colours that were already legal. BT.2100 keeps narrow range as the default for HDR and introduces a full-range option that it says should not be used for exchange unless everyone involved agrees.
| Bit depth | Narrow range, black to white | Full range | Narrow file read as full | Full file read as narrow |
|---|---|---|---|---|
| 8-bit | 16–235 | 0–255 | black at 6.3%, white at 92.2% | black at -7.3%, white at 109.1% |
| 10-bit | 64–940 | 0–1023 | black at 6.3%, white at 91.9% | black at -7.3%, white at 109.5% |
| 12-bit | 256–3760 | 0–4095 | black at 6.3%, white at 91.8% | black at -7.3%, white at 109.6% |
| Standard | Publisher | Edition | What it is | Limit of this record |
|---|---|---|---|---|
| ITU-R BT.709 | ITU-R | BT.709-6 (06/2015), in force | Parameter values for HD television: the primaries shared with sRGB, a D65 white and the camera-side transfer function. | Defines the camera curve, not the display's; that is BT.1886. |
| ITU-R BT.2020 | ITU-R | BT.2020-2 (10/2015), in force | Parameter values for ultra-high-definition television, including primaries far more saturated than BT.709's. | Used mostly as a container: masters are graded inside a smaller gamut and carried in it. |
| DCI-P3 | SMPTE, as registered by the ICC | SMPTE EG 432-1:2010 | The digital-cinema projector colour space: P3 primaries, a greenish DCI white point and a 2.6 gamma. | Not the same as Display P3, which pairs the same primaries with D65 and the sRGB curve. |
| Digital Cinema Package | Digital Cinema Initiatives | Specification 1.0 (2005) to 1.4.1 (2021) | The package sent to cinemas: JPEG 2000 picture wrapped in MXF, with separate profiles for 2K and 4K. | Described from the Library of Congress summary; the specification's colour clauses were not read. |
| EBU R 103 | European Broadcasting Union | Version 3.0 (May 2020) | Tolerances for video signal levels: the nominal and preferred ranges of code values, how to measure them and when an excursion counts as a gamut error. | A recommendation; each broadcaster's delivery specification decides what is rejected. |
Why: Saturated bright or saturated dark colours whose colour-difference values de-matrix to red, green or blue outside the preferred range.
Fix: Find the shots with a gamut display, pull back saturation or level on the offending colours in the grade, then re-measure with the recommended filtering.
Why: Sharpening, scaling or keyed graphics overshoot at transitions.
Fix: Reduce sharpening, build graphics inside nominal levels, and check after the final scale, not before.
Why: A clip was applied to channels individually, flattening gradients and changing channel ratios.
Fix: Remove the legaliser, correct the shots in the grade with a soft roll-off, and re-apply the legaliser only as a final safeguard.
Why: Colours inside the HDR volume map outside the BT.709 nominal range on conversion.
Fix: Review the conversion shot by shot; the EBU tolerance allows such colours inside the preferred range, but a stricter broadcaster's specification may not.
Each statement is labelled by kind — established fact, a standard’s requirement, observed market data, a convention, or Colourwise’s own interpretation or analysis — with the strength of the evidence behind it.
StandardStrong evidence
EBU R 103 version 3.0 recommends that RGB components and the corresponding luminance signal should not normally exceed a preferred range slightly wider than the nominal video range, and defines signals outside the preferred range as gamut errors.
Source: EBU R 103: Video Signal Tolerance in Digital Television Systems, version 3.0
StandardStrong evidence
EBU R 103 version 3.0 recommends that measuring equipment indicate an out-of-gamut occurrence only after the error exceeds one per cent of the image, measured after filtering and excluding signals outside the active picture.
Source: EBU R 103: Video Signal Tolerance in Digital Television Systems, version 3.0
StandardStrong evidence
ITU-R BT.2035 sets reference white at 10-bit code value 940 and reference black at code value 64 for the display used to evaluate HD programmes.
Colourwise analysisStrong evidence
Narrow range leaves 876 of the 1,023 steps of a 10-bit scale between nominal black and white, about 86 per cent, the rest being margin below black and above white.
Based on: Calculated by Colourwise: 940 minus 64 is 876, divided by 1,023.
Source: EBU R 103: Video Signal Tolerance in Digital Television Systems, version 3.0; Recommendation ITU-R BT.2035: A reference viewing environment for evaluation of HDTV program material or completed programmes
Colourwise interpretationModerate evidence
The R 103 figures are a recommendation, and what a given broadcaster or streaming service rejects is set by its own delivery specification, which may be stricter.
Based on: R 103 describes itself as guidelines for measuring and assessing levels and asks that pre-produced material follow nominal limits closely; delivery specifications are separate documents.
Source: EBU R 103: Video Signal Tolerance in Digital Television Systems, version 3.0
Reviewed 6 October 2026. Colourwise summarises its sources in its own words and does not reproduce standards text or proprietary colour data. Spotted an error? Tell us.