The HDR Abstract
This abstract takes a look into High Dynamic Range (HDR) video. We'll dissect the core concepts that enable HDR to deliver a more realistic and immersive viewing experience by expanding luminance and color far beyond the limits of Standard Dynamic Range (SDR). Use the interactive charts and comparisons below to understand the quantifiable benefits of this technology.
Dynamic Range (Stops of Light)
HDR captures significantly more detail in the brightest and darkest areas of an image.
Bit Depth & Color Representation
Higher bit depth reduces color banding and allows for smoother, more accurate gradients.
The Human Factor: Why HDR Matters
The design of HDR technology is fundamentally driven by the capabilities of the Human Visual System (HVS). HDR aims to create an image on screen that more closely matches what our eyes perceive in the real world in terms of brightness, contrast, and color. This section explores the key perceptual phenomena that HDR technologies are engineered to accommodate.
Luminance Perception & Weber-Fechner Law
Our eyes don't perceive brightness linearly. We are far more sensitive to changes in dark areas than in bright ones. HDR's Perceptual Quantizer (PQ) transfer function is based on this principle, allocating more data to the shadow and mid-tone details our eyes are most sensitive to, optimizing data efficiency.
Color Perception & Rec. 2020
The human eye can perceive a vast range of colors. HDR leverages the Wide Color Gamut of Rec. 2020 to reproduce a larger portion of these colors compared to SDR's Rec. 709, resulting in richer, more lifelike images.
Comparing Color Gamuts
Visualize the expanded color range of Rec. 2020 compared to the traditional Rec. 709 gamut.
Core Technologies: Transfer Functions
Transfer functions are mathematical models that map digital code values to light levels on a display. HDR uses advanced transfer functions like Perceptual Quantizer (PQ) and Hybrid Log-Gamma (HLG) to manage its vast dynamic range, each with distinct characteristics and applications. The chart below visualizes how they map signal values to absolute luminance.
Perceptual Quantizer (PQ)
An absolute, perceptually uniform transfer function designed for mastering. It maps code values to absolute luminance levels (nits) up to 10,000 nits, making it ideal for cinematic content where precise creative control is paramount. It relies on metadata for optimal display on consumer devices.
Hybrid Log-Gamma (HLG)
A relative, display-referred transfer function designed for broadcast. Its key advantage is backward compatibility; a single HLG signal can be displayed on both HDR and SDR screens without special metadata. This makes it a practical solution for live production and broadcasting.
HDR Formats & Display Technologies
The HDR landscape consists of various formats and display technologies, each with unique technical specifications and ecosystem support. Use the tabs below to compare the leading HDR formats and the display technologies that bring them to life. This comparison is vital for engineers making decisions in production, distribution, and hardware evaluation.
HDR Format Comparison
HDR Display Technology Comparison
The HDR Production & Distribution Workflow
Engineering HDR video requires a comprehensive approach across the entire pipeline, from initial capture to final delivery. Each stage has unique technical considerations to ensure the integrity and quality of the HDR signal is maintained, delivering a consistent and high-quality experience to the viewer regardless of the distribution channel.
Acquisition
Capture using cameras with high dynamic range sensors (14+ stops), 10/12-bit depth, and log encoding formats to preserve maximum detail.
Post-Production
Grade in a calibrated HDR suite, working in nits. Manage color spaces and use HDR-specific tools to adjust tone mapping and master for various formats (HDR10, Dolby Vision, etc.).
Distribution
Deliver via streaming (DASH/HLS with HEVC/AV1 codecs), broadcast (ATSC 3.0), or physical media (Ultra HD Blu-ray), ensuring metadata is preserved across the channel.
Is HDR a "Scam"?
While HDR technology offers objectively superior capabilities, it is sometimes labeled a "scam" by consumers. This perception doesn't stem from flaws in the technology itself, but from its frequent misuse and mishandling across the ecosystem. The highly standardized and mature nature of SDR means that most content and displays deliver a consistent, predictable experience. HDR, being more complex, introduces more points of failure. When HDR content is poorly mastered with incorrect metadata, or when displays marketed as "HDR compatible" lack the necessary peak brightness, contrast, or color gamut to render it properly, the result can be an image that looks worse than its SDR counterpart—often appearing too dark, washed out, or with unnatural colors. This inconsistent and sometimes disappointing outcome, driven by poor implementation rather than technological shortcomings, is the root of the "scam" narrative.
TLDR: HDR is not a scam, it is a very powerful technology that is easy to misuse.