What is HDR?HDR10 HDR10+ HDR10+ Adaptive HLG Dolby Vision Dolby Vision IQ HDR Pro, Plus...SVODCOMMENTS

HDR is by far the new queen technology in recent years to improve the quality of the display of our screens.However, we drown between the labels: HDR10, HDR10+, HLG, Dolby Vision… The acronyms are multiplying.It is time to explain their differences.

HDR is undoubtedly the most important technology released in recent years for our screens.Covering a wider range of brightness, it allows you to find black black blacks, white whites, ever more nuanced colors and variations in intensity and brightness within the same image.

What make an ever more impressive experience.However, meeting it as a consumer is complicated, since standards have multiplied.Our file will explain the ins and outs of the main HDR labels.

HDR, what is it?

Since the beginning of time, the visual arts have always sought to recreate a scene as original and as faithful as possible to make as in real life.We started with painting, drawing and then arrived photography and cinematography.Until recently, reproductive efforts were limited to a restricted dynamic range symbolized by the difference in brightness in reproduction of the darkest possible black with that of the most brilliant white.

The dynamic range of an image (Dynamic Range) represents the measurement measured between the clearest area and the darkest part.Thus, logically, the more the dynamic range is extended and the more the image appears as contrasting both in dark areas and clear areas;The more the colors are rich and subtle.

The human eye can adapt to a wide range of light intensity levels.The brightness beach that people can see is much higher than the contrast range available on current screens as shown in the figure below.

A high dynamic range was therefore designed to capture, treat and reproduce scene with increased details in shadows and highlights beyond the current capacities of SDR video and cinema systems.The concept of HDR (High Dynamic Range) is actually to be put into perspective with that of SDR, Standard Dynamic Range which is designed for standard images.The SDR draws its specifications from the characteristics of the old cathodic tube screens which are no longer used today.The possibilities are relatively reduced.HDR systems are therefore intended to offer more noticeable details in shadows and high lights which corresponds better to the human visual system in different image visualization conditions.

Do not reduce HDR to brightness

To properly enter the concept of HDR, it must be noted that contrary to what we can hear here or there like what HDR produces globally brighter images, HDR actually offers a wider range of luminance so blacksdeeper and brighter reflections with in particular light which can be reflected on brilliant objects.Most of the time, we tend to associate the concept of HDR only with technologies relating to "brighter" images whose peak is measured in CD/m².

Of course, brightness is a major element of HDR, but that does not do everything.HDR encompasses the entire range of tonal values from black to clear.Some call it gray or graycal levels in English.HDR allows us to appreciate the whole gray scale and not only the values that concern highlights, but also shadows and subtle gradations between the two extremes.

R-BT.2020: a question of encoding

Digital video systems use a certain quantification for coding gray levels.For the high -definition general public format, it is 8 -bit encoding.If it can be suitable for SDR images, it is insufficient for HDR.Thus, the ITU (International Telecommunications Union) was able to define a new standard.Called R-BT.2020 For the Ultra HD, it made it possible to significantly extend the gray levels thanks in particular to a 10 -bit encoding for the general public.For professionals, a 12 -bit quantification option is available to go even further.

Like any technology, it is obvious, but it is better by saying it, to take advantage of the HDR, it is necessary that the devices are compatible and carrying the HDR mention.

What is HDR10?

HDR10 is a standard that is based on an open platform.It is thus named, because its quantification scale is based on 10 bits within the BT color space.2020.Each hardware manufacturer can get caught up to make its devices compatible and thus offer users the benefits of such technology on their screens.It makes it possible to display a wider palette of colors and shades compared to classic images encoded on 8 bits in the color space.709.It uses the SMPTE ST 2084 EOTF standard which is based on the real sensitivity of the human eye concerning the contrast and making it possible to cover a maximum luminance of 10,000 cd/m².

The problem with HDR10 is that the specifics of the video are defined once for all sequences.It therefore lacks a notion of dynamism, because certain scenes may require certain adjustments to others.

What is HDR10+?

HDR10+ is an evolution of HDR10.It has been developed to better compete with the Dolby Vision format.Like him, HDR10+ uses dynamic metadata that are integrated within the video stream in order to be able to modulate the answer according to the scenes and thus optimize the rendering.This standard is supported by several major players in the electronics industry including the 20th Century Fox, Panasonic and Samsung since 2018.In August 2021, the HDR10+ format claimed 120 partners, including television manufacturers, but also smartphones brands, touch pads and Blu-ray readers.On this date, 2000 content supports this format.

What is HDR10+adaptive?

HDR10+ adaptive is an evolution of HDR10+.Launched since 2021, he not only supports the dynamic metadata of the video flow, but still adjusts the images a little more in order to adapt to the room lighting conditions.To do this, the diffuser uses a light sensor in order to optimize the scenes as the director would have liked by limiting the loss of details and contrast according to the ambient light.The HDR10+ adaptive competes with the Dolby Vision IQ format which uses the same principle of adaptability according to the lighting conditions of viewing.

What is HLG?

The HLG format (Hybrid Log Gamma) is a hybrid -free hybrid technology that combines SDR images and HDR images combined in a single video flow.Like HDR, it is based on an EOTF system, but hybrid here (electro optical transfer fun) which allows you to transform digital information into an electrical signal to create light on the screen.This technology makes it possible to simplify the transmission of TV channels and thus to satisfy simultaneously and with the same flow both the most technically limited TVs as the others more advanced.

What is Dolby Vision?

The Dolby Vision format is an HDR format.But unlike HDR10, it is not free of rights.It is the property of the Dolby laboratories.To take advantage of it, the reading and distribution devices must be compatible Dolby Vision.The HDR character is not enough.The Dolby Vision video flow is encoded on 12 bits.

Like the HDR10+format, it uses dynamic metadata to optimize images in terms of brightness, contrast and colorimetry according to the scenes of the.Compared to HDR10+, he benefits from a particularly rigorous calibration monitoring and control from production studios to the final consumer television.

What is Dolby Vision IQ?

This is an evolution in the Dolby Vision format.It can be compared to HDR10+ adaptive in the sense that it uses a brightness sensor installed on the diffuser to measure the amount of light in the room.Thus, working in concert with the diffuser processor, it allows you to adjust the properties of the image to try to obtain the best rendering possible from a Dolby Vision source.This option can be deactivated on the devices that offer it, if applicable.

What is HDR Pro, HDR Plus and others?

All other appellations such as HDR Pro, HDR Plus, etc..refer to marketing notices and absolutely do not correspond to technologies embedded by readers or TV.It is a question for manufacturers to highlight technical characteristics deemed as being superior to those proposed by the SDR, but which do not fully meet the specifications requested for the use of HDR, offering, ultimately, an incomplete experience.

What SVOD services are HDR10, HDR10+ and Dolby Vision compatible?

Le format HDR10 est proposé sur les plateformes françaises Netflix, Prime Vidéo, Disney+, AppleTV+, Google Play Movies & TV, Rakuten TV et YouTube.

The HDR10+ format is available on the French platforms of Google Play Films and TV, Video Prime, Rakuten TV and YouTube.

The Dolby Vision format is offered on Netflix, Disney+ and Apple TV+.

Some UHD Blu-ray discs offer content in HDR and/or Dolby Vision version.TNT is limited for the moment to a few tests of retransmissions of punctual sporting events and only available from the issuer of the Eiffel Tower.

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