HDR10

HDR10 is an open media format for high dynamic range (HDR) video, composed of a combination of industry standards rather than a single video codec. The “10” in its name refers to the fact that consumer releases typically use 10-bit quantization. HDR10 is widely adopted by televisions, monitors, game consoles, streaming services, and Ultra HD Blu-ray, and serves as the foundational compatible format for a variety of HDR playback devices.

HDR10 uses the Perceptual Quantizer (PQ) defined in SMPTE ST 2084 as its electro-optical conversion function. The PQ is based on absolute display brightness and maps digital code values to a theoretical range of up to 10,000 cd/m². This upper limit represents the encoding boundary of the transfer function and does not imply that HDR10 programs must be produced or played back on a 10,000-nit display. Commercial master copies often use reference displays in the 1,000, 2,000, or 4,000 nit range, and the maximum pixel brightness in the actual image may also be lower than the peak of the master display. Color signals typically use the chromaticity coordinates and matrix coefficients of ITU-R BT.2020, and 4:2:0 chroma subsampling is common in compressed video. The BT.2020 tag defines the signal container but does not guarantee that the program actually uses the full BT.2020 color space; much content is color-graded within the P3 range and then encapsulated in a BT.2020 container. The 10-bit quantization of HDR10 provides 1,024 encoding levels per component, which can reduce banding in wide luminance gradients; however, the final result is still affected by compression, processing accuracy, and the display panel.

The metadata for HDR10 consists primarily of static information. SMPTE ST 2086 records the chromaticity coordinates, white point, and maximum and minimum luminance of the master display; The CTA-861 system also defines MaxCLL and MaxFALL, which represent the maximum pixel luminance level and the maximum frame average luminance level of the content, respectively. These values provide a set of descriptors for the entire program segment; they do not change frame by frame with shots or scenes, and some files or production workflows may lack one or more of these values.

After a display device receives PQ video and static metadata, it must map the program’s brightness range to the capabilities of its own panel. If the brightest parts of the content exceed the display’s peak brightness, the TV may employ tone-mapping strategies such as clipping, compression, or clipping; different manufacturers and picture modes may yield different results. HDR10 does not specify a single tone mapping algorithm for display devices; therefore, the highlight detail, overall brightness, and color saturation of the same bitstream may vary across different devices.

HDR10 is independent of video encoding. Ultra HD Blu-ray uses HEVC Main 10 to carry HDR10, while streaming services may use HEVC, VP9, AV1, or other codecs that support the corresponding signals and metadata. Resolution is also not a prerequisite for HDR10: HDR10 can be combined with 1080p, 2160p, or other resolutions, and 4K video can also be in standard dynamic range. The presence of “4K” in a filename or packaging does not serve as a substitute for HDR format identification.

Display chains that do not support HDR cannot correctly interpret PQ signals according to SDR rules. Players or televisions must perform HDR-to-SDR conversion; otherwise, the image may exhibit abnormal brightness or color distortion. The interface must also transmit the appropriate color and HDR identifiers; incompatibilities in HDMI version, EDID negotiation, color depth settings, or intermediate devices may cause the playback device to output SDR, alter the color format, or fail to enable HDR.

HDR10+ and Dolby Vision employ dynamic metadata schemes on top of the HDR10 foundation, allowing the display to adjust the mapping on a scene-by-scene or frame-by-frame basis. These are not features inherently included in HDR10. On Ultra HD Blu-ray, HDR10+ and Dolby Vision are typically distributed with additional data alongside a HDR10-compatible base video; devices that do not support the extensions can still read the base HDR10; The specific compatibility structure varies depending on the format and application configuration.

HLG is another HDR delivery system defined by ITU-R BT.2100, primarily intended for broadcast workflows; it does not use PQ’s absolute luminance encoding. Collectively referring to all 10-bit HDR video as HDR10 can cause confusion between PQ, HLG, and other formats. Accurate identification requires examining the transfer function, primary colors, bit depth, and metadata simultaneously; it cannot be determined solely based on the image appearing brighter or the presence of “BT.2020” in the media metadata.