SDR, short for standard dynamic range, is the conventional video format in which images are mastered for a reference peak luminance of about 100 nits using a gamma-based transfer function and, in most cases, the Rec. 709 color gamut. In HDR video, SDR is the baseline against which high dynamic range formats are defined and compared.
The term appeared only when HDR arrived; before that, SDR was simply video. It still covers the vast majority of broadcast, streaming, archive and web content, and every HDR production must normally deliver an SDR version for viewers whose screens or services do not support HDR.
How SDR encodes brightness and color
SDR encodes brightness with a relative gamma curve rather than absolute light levels. The signal states how bright a pixel is as a fraction of the display’s white, and the BT.1886 reference display maps that signal with an effective gamma of about 2.4 in a dim grading environment.
Color is usually defined by ITU-R BT.709 primaries, the same gamut used for HD television and close to the sRGB space of computer displays. Most delivery files use 8-bit encoding, while professional masters often use 10 bits to reduce banding.
The table below summarizes the main technical parameters of a typical SDR video signal.
| Parameter | Typical SDR value | What it controls |
|---|---|---|
| Reference peak luminance | About 100 nits | Brightness of reference white |
| Transfer function | Gamma, BT.1886 reference about 2.4 | Mapping of signal to light |
| Color gamut | Rec. 709 primaries | Range of reproducible colors |
| Bit depth | 8-bit delivery, 10-bit mastering | Number of tonal steps |
| Signal range | Limited range, 16 to 235 in 8-bit | Legal black and white levels |
| Usable dynamic range | Roughly 6 to 7 stops on screen | Contrast between shadows and highlights |
SDR compared with HDR formats
The essential difference is how much brightness and color the signal can describe. HDR formats such as HDR10, HDR10+ and Dolby Vision use the PQ transfer function, which encodes absolute luminance up to 10,000 nits, while HLG uses a relative hybrid curve designed for broadcast.
| Format | Transfer function | Typical mastering peak | Metadata |
|---|---|---|---|
| SDR | Gamma, BT.1886 | About 100 nits | None required |
| HLG | Hybrid log-gamma, relative | Commonly 1,000 nits | None required |
| HDR10 | PQ, absolute | Often 1,000 to 4,000 nits | Static, MaxCLL and MaxFALL |
| HDR10+ | PQ, absolute | Often 1,000 to 4,000 nits | Dynamic, per scene |
| Dolby Vision | PQ, absolute | Often 1,000 to 4,000 nits | Dynamic, per shot or frame |
HDR usually pairs with a wide color gamut inside a Rec. 2020 container, while SDR mostly remains in Rec. 709. However, dynamic range and gamut are separate properties; a Rec. 2020 SDR signal is possible, though rare in practice.
A key consequence is highlight behavior. In SDR, specular reflections, the sun and bright skies must be compressed into the same small range above diffuse white, so they look less intense than in HDR, where those highlights can rise several stops above the brightness of a white shirt.
SDR on real displays
Although SDR is mastered at about 100 nits, consumer televisions, phones and monitors usually display it much brighter, often 200 to 500 nits depending on the device and viewing mode. Because SDR is relative, the display simply scales the whole image to its chosen white level.
This relative behavior makes SDR robust and predictable: content looks broadly as intended on almost any screen. The downside is that creative intent is less controlled, since each display chooses its own brightness, contrast and color processing.
| Environment | Typical white level | Effect on SDR content |
|---|---|---|
| Grading suite | About 100 nits, dim surround | Reference appearance |
| Living room television | About 200 to 400 nits | Brighter, contrast may be boosted |
| Smartphone outdoors | Several hundred nits or more | Readable in daylight, colors shift |
| Computer monitor with sRGB | About 80 to 250 nits | Slightly different gamma |
| HDR display showing SDR | Set by SDR brightness option | Mapped into the HDR range |
Delivering SDR alongside HDR
Most HDR productions require a matching SDR deliverable. There are three main approaches: a separate SDR trim pass graded by a colorist, an automatic HDR-to-SDR conversion through tone mapping, or dynamic metadata such as Dolby Vision that generates the SDR version from analysis and trims.
HLG takes a different route. Its curve is designed so that an HLG signal looks acceptable on SDR displays that support Rec. 2020, which suits live broadcast where producing two separate feeds is costly.
| Approach | How it works | Trade-off |
|---|---|---|
| Separate SDR grade | Colorist grades SDR independently | Best control, highest cost |
| Trim pass from HDR | SDR derived with manual adjustments | Good control, moderate effort |
| Automatic tone mapping | Algorithm compresses HDR to SDR | Fast, may flatten highlights |
| Dolby Vision analysis | Metadata drives the SDR derivation | Consistent, needs licensed tools |
| HLG compatibility | One signal for both display types | Simple, less SDR-specific control |
Common SDR mistakes and misconceptions
The most frequent misconception is that SDR means low quality. A well-graded SDR image in 10-bit can look excellent; HDR adds highlight headroom and color volume, but it does not by itself make an image sharper or better composed.
- Gamma tag mismatches: exporting with the wrong transfer tag makes SDR look washed out or too dark in some players.
- Clipped highlights from poor conversion: careless HDR-to-SDR mapping loses detail in skies and windows.
- Grading on uncalibrated screens: a bright consumer display hides problems that appear on reference monitors.
- 8-bit banding: heavy grading of 8-bit sources produces visible steps in smooth gradients.
- Assuming SDR is obsolete: many platforms, devices and archives still depend on SDR masters.
A reliable practice is to check every SDR deliverable on a calibrated Rec. 709 display and on typical consumer devices. Comparing the SDR and HDR versions side by side also reveals whether tone mapping has preserved the intended contrast and skin tones.
The simple explanation
SDR is the ordinary type of video that most screens have shown for decades. It describes how bright and how colorful the picture is allowed to be, and that range is fairly modest.
HDR video can show much brighter highlights and richer colors, a bit like the difference between a regular photo print and a backlit display. SDR remains the common language that almost every television, phone and computer understands.
How it is used in practice
A streaming documentary is graded in HDR at a 1,000-nit peak in PQ with Rec. 2020 primaries. The platform also requires an SDR deliverable in Rec. 709 at gamma 2.4 for viewers on older televisions, laptops and phones.
The colorist runs a trim pass from the HDR grade, pulling sunlit skies down so they keep texture and lifting dark interiors slightly to preserve shadow detail at 100 nits. She checks the result on a calibrated SDR monitor and a typical phone. Both versions now share the same look and skin tones, even though the SDR one uses a fraction of the brightness range.