What is HDR?

High Dynamic Range (HDR) is a technology that produces images with a large perceptible difference between bright and dark regions. This capability achieves lifelike images and preserves precise details in lighting variations and gradations for realistically bright or dark pictures without subtle detail loss.

HDR requires a fast connection for the display. Popular connections such as HDMI 2.0 and DisplayPort support HDR, but high resolutions at refresh rates greater than 60Hz will require the higher-bandwidth DisplayPort 1.4.

HDR monitors produce realistic picture quality to replicate original images. With this new dynamic range compressing technology, an HDR display fully samples bright-dark tone variation within a scene to avoid overexposure of bright images as well as prevent lost details in dark images. In addition, HDR monitors represent true colors, unlike conventional SDR displays. Catering to consumer preferences, SDR monitors typically display images with an artificially strong hue. However, HDR technology accurately recreates original colors, reproducing true colors even in dark areas as seen in real life by the naked eye. And in order to show perfect picture quality, HDR image reproduction requires filmed content in the master tape to be tuned by professional engineers to the tone and color gamut appropriate for playback on the HDR display.

A monitor’s color gamut is the total range of colors it can produce with its red, green, and blue primary colors. Any color that blends these primary colors and lies between them can be produced, but the display cannot create a color that is not inside the triangle between its primary colors, outside its color gamut. Conventional SDR displays are typically limited to the Rec.709 color gamut, an international standard for HDTV formats, but today’s HDR displays expand that triangle to encompass more of the total spectrum of colors human eyes can detect by using special and customized LCDs that accommodate the larger DCI-P3 color gamut. Broadly used by Hollywood and broadcast industries, DCI-P3 offers significantly greater range of colors than the Rec.709 color gamut, as well as a wealth of existing equipment and content that support it.

HDR monitors strive to produce a close replica of extremely bright scenes by using a common Electro-Optical-Transfer-Function (EOTF) which ensures that images will be closer to what human eye see. What this means for human perception is that the range of HDR brightness is significantly greater than SDR. This results in true, subtly variegated greyscale gradation, and clearly distinct fine details in predominantly bright as well as mostly dark scenes.

Common specifications for a display’s resolution include 720p, 1080p, and 2160p or 4K. Indicating the number of horizontal lines on the display, these numbers correspond to the following resolutions including the number of dots across each horizontal line:

• 1080p resolution (FHD or Full HD) is 1920 x 1080 lines = 2 million pixels
• 1440p resolution (QHD or Quad HD) is 2560 x 1440 = 3.6 million pixels
• 2160p resolution (4K, UHD, or Ultra HD) is 3840 x 2160 = 8.3 million pixels

Upgrading to these higher resolutions provide significantly improved picture quality with sharp clarity, as well as enabling larger panel sizes which would look pixelated and blurry with low resolution.

Apart from resolution, HDR enhances the monitor's contrast ratio, which is the luminance difference between the brightest and darkest images the display is able to show. A larger contrast ratio allows significantly more details to be revealed between the bright and dark extremes. In addition, by increasing the contrast, HDR displays deliver pristinely bright whites and superbly deep blacks as well as intensely saturated and vibrant colors, resulting in HDR images that appear more realistic and vividly stand out.

Working to enhance the brightness, contrast, color, and detail performance of displays, HDR is an independent technology to the monitor’s resolution. Display panels with HD, FHD, QHD, and UHD resolution can all support HDR, but only when that panel is qualified to HDR standards.

VESA DisplayHDR certification is the world’s first public qualification testing protocol for HDR monitor performance. VESA DisplayHDR certification assures consumers that the certified display can flawlessly render HDR content with brilliant peak brightness and contrast, deeper blacks and clear dark details, and true color tones for naturally realistic video and gaming quality.

Please refer to following page to learn more about Display HDR: https://displayhdr.org/performance-criteria/

HDR10 is a standard adopted widely by most international monitor brands, as many major companies have implemented the HDR10 protocol. Defined jointly by the Blue-Ray Association, HDMI Forum and UHD Association, HDR10 is the format that supports the compressed transmission of HDR video content. HDR10 is officially defined as the format that supports HDR content by CEA on August 27, 2015. One of the key factors to fulfill the requirements of HDR monitor is the ability to decode files of HDR10 format.

Files of HDR 10 format need to fulfill the following criterion in order to match with the HDR format:

1. EOTF (electro-optical transfer function)：SMPTE ST 2084
2. Color Sub-sampling：4:2:2/4:2:0 (for compressed video sources)
3. Bit Depth：10 bit
4. Primary Color：ITU-R BT.2020
5. Metadata：SMPTE ST 2086, MaxFALL, MaxCLL

**SMPTE ST 2086 "Mastering Display Color Volume" static metadata to send color calibration data of the mastering display, such as MaxFALL (Maximum Frame Average Light Level) and MaxCLL (Maximum Content Light Level) static values, encoded as SEI messages within the video stream.

DisplayHDR version 1.0 focuses on liquid crystal displays (LCDs), establishing three distinct levels of HDR system performance to facilitate adoption of HDR throughout the PC market: DisplayHDR 400, DisplayHDR 600, and DisplayHDR 1000. HDR 10 refers to a standard adopted widely by most international monitor brands, and it is the format that supports the compressed transmission of HDR video content. For monitors of all levels, they are all required to support the industry standard HDR-10 format in order to properly display HDR content.