UHD LOGO - TECHNICAL REQUIREMENTS
DIGITALEUROPE has finished the development of an Ultra HD logo and its associated parameters. The three points given below detail the approach we have taken towards a logo and explain our choice of parameters.
- UHD displays have appeared on the market and their number is forecasted to increase greatly in the upcoming years. There is a significant risk of unpredictable quality performance and lack of interoperability of some Ultra HD products.
- The purpose of the logo is to propose a common baseline through a set of technical parameters, fostering interoperability and optimal overall performance of products with the Ultra HD logo. For any parameter values beyond DIGITALEUROPE’s minimum requirements, the player may have to provide a conformant baseline signal unless the negotiation between source device and display results in higher capability.
- Parameter choice: Our UHD Display parameters were selected in order for a sufficient number of upcoming devices to qualify for the logo in line with what the technology can offer today to medium term.
About the specifications
A display device has to cover the following requirements to be awarded the "DIGITALEUROPE UHD Display" logo:
Display and display engine
- The minimum native resolution of the display (e.g. LCD, PDP, OLED) or display engine (e.g. DLP) is 3840 x 2160 in 16:9 aspect ratio.
- The minimum supported colorimetry shall be according to BT.709
- The display-device shall have at least one end-to-end signal path available to the user that does not render a UHD Input at a frame rate or resolution lower than that received over the UHD Interface from the source.
- The display-device shall have at least one end-to-end signal path available to the user that does not reduce the resolution nor shall it reduce the frame rate of a UHD Input during processing prior to display.
Note #1 Clarification for the avoidance of doubt: This requirement is carefully worded such that it allows for well-known display practices such as quarter screen video display as part of an EPG, where clearly a reduction of resolution will be necessary, but that in normal full screen television viewing mode the device has a user option to at least maintain the resolution and frame rate at each and every stage of its internal processing, from input to rendering. For example, a device which only has the possibility to downscale the resolution to HD resolution after input and later up scales it again to UHD resolution for rendering does not comply with UHD Display logo requirements.
The display device accepts UHD input via HDMI. It shall support HDCP 2.2 Copy Protection.
UHD capable inputs accept UHD video signals:
- with a resolution of 3840 x 2160 pixels
- at frame rates 24p / 25p / 30p / 50p / 60p
- with a minimum supported bit depth of 8 Bit
- at a chroma sub-sampling rate of 4:2:0 for 50p/60p and 4:2:2 for 24p/25p/30p
- with minimum supported colorimetry according to BT.709
A device that renders audio shall be able to accept and present at minimum a PCM 2.0 stereo signal, delivered at the HDMI connector together with the UHD video signal.
The HDCP2.2 content protection satisfies higher requirement on content protection expressed by some major studios.
A display device may exceed the requirements above. Additional display capabilities can be signaled over the HDMI interface and, if supported by the display as well as by the signal source, these additional capabilities can be used without requirement for downscaling to the minimum requirements.
These specifications define the minimum baseline. The sections below give background of the current choice of parameters/technologies
The native resolution 3,840x2,160 is the agreed resolution in standards for UHD. It offers 4 times more pixels than the Full HD resolution. Progressive format as included in the DE Logo requirements produces a higher quality image than interlaced picture frames.
Today, 16:9 is the aspect ratio typically used for television.
Recommendation ITU-R BT.709 is a baseline for TV signals and provides widest compatibility in the market.
Recommendation ITU-R BT.2020 anticipates future advances in display technology. In 2015, no consumer or professional display could fully render ITU-R BT.2020. If a source device uses ITU-R B.T2020 colour gamut, that source would need to offer a proper down conversion to ITU-R BT.709 in order to ensure a correct colour rendering.
Colour Bit depth
DIGITALEUROPE UHD logo requirements are minimum requirements to ensure interoperability between display devices and source devices. 8-bit is the baseline to achieve this interoperability.
If a source signal (broadcast transmission or media player) has a bit value of 10 or 12, then the media players or receivers interfacing with the UHD Display will need to convert down to 8 bits if the display supports only 8 bits. Alternatively, a higher bit value may be used depending on negotiation of the interface capabilities between source and display, according to HDMI.
The specified frame rates (24p/25p/30p/50p/60p) are defined by BT.709 and also fit the frame rates currently used for the highest quality HD transmissions. 50-60 fps progressive represents a significant improvement on High Definition and has been demonstrated to provide good motion portrayal for fast-moving action such as sports. This could be verified during the French open and during the FIFA World Cup. Typically, fictional and documentary content is captured at 24 fps. UHD content at 50fps shall be both decoded and displayed with at least 50 fps.
Research into use of higher frame rates is ongoing, particularly in terms of cost/benefit as well in relation to efficiency of bandwidth.
The requirement for audio is 2 Channel PCM audio. Typically, television sets are not equipped to render multiple-channel audio, i.e. they are stereo. They do, however, output multichannel audio formats to an external receiver. This is, however, typically specified elsewhere. The DIGITALEUROPE logo ensures basic interoperability.
High Dynamic Range
HDR can enhance the UHD experience. However, as there is no single HDR system but many different techniques which may vary or compete in the market depending on source, media or content provider, HDR is not included in the UHD logo requirements.
UHD Display devices and UHD television broadcasts
It is not the target of DIGITALEUROPE’s UHD-display logo to reference the reception capability of devices. This logo concerns basic physical screen parameters, minimum display capabilities, and basic audiovisual signal parameters to be accepted at an HDMI connector. Our intention is to foster basic interoperability, and that Ultra HD display devices are physically true Ultra HD displays, and not of a lower resolution, but just accepting Ultra HD signals at their inputs.
Profiles for broadcasting UHD have been standardised in DVB. The fundamental picture resolution of DIGITALEUROPE UHD Displays and UHD TV broadcasts will be identical.
DIGITALEUROPE UHD Displays can render DVB UHD TV broadcasts at full resolution,
UHD broadcasting is still at its infancy with broadcasters performing trials. We encourage broadcasters to embrace the new technology if they are to offer their viewers the best image quality available. In the meantime, consumers can enjoy UHD with a growing number of online services, packaged medias and devices.