High dynamic range
HDR technology captures a broader spectrum of light and dark details, replicating a more realistic visual experience. Compared to standard displays and content, HDR showcase richer colors, deeper blacks, and brighter highlights with preserved details. While SDR struggle with the full range of light in a scene, HDR allows for a more natural representation. HDR content is created by combining multiple exposures, resulting in an image closer to what our eyes perceive.
HDR Rendering Pipeline
[edit | edit source]High-dynamic-range rendering (HDRR or HDR rendering), also known as high-dynamic-range lighting, is the rendering of computer graphics scenes by using lighting calculations done in high dynamic range (HDR). This allows preservation of details that may be lost due to limiting contrast ratios. Video games and computer-generated movies and special effects benefit from this as it creates more realistic scenes than with more simplistic lighting models. HDRR was originally required to tone map the rendered image onto Standard Dynamic Range (SDR) displays, as the first HDR capable displays did not arrive until the 2010s. However if a modern HDR display is available, it is possible to instead display the HDRR with even greater contrast and realism.[1]
Process of SH Lighting and HDR rendering;
- Designed to work with a wide dynamic range from the start.
- Lighting and color calculations are performed with HDR in mind, preserving a broad spectrum of brightness and color data.
- On an HDR display, this data is shown directly, with minimal compression, for vivid visuals.
- If displayed on an SDR screen, tone mapping compresses the HDR data to fit the narrower range.
e.g., 
Double Steal: The Second Clash, Source-engine titles, see Game engines that support HDR rendering list for more. The GameCube and Wii don't support HDR rendering in any capacity. There is no HDR source to dig out.[2][3]
Native Emulator Pipeline Implementations
[edit | edit source]Rather than using external post-processing tools to fake an HDR look, some standalone emulators actively refactor their rendering engines to output a true, uncompressed HDR signal directly to the display swapchain:
- PCSX2 (PlayStation 2): Ongoing development experiments with native HDR swapchain creation, color translation, and direct display output support to handle internal retro calculations natively without forcing an SDR container constraint first.[4]
VESA DisplayHDR Standards (Hardware)
[edit | edit source]These tiers certify the physical capabilities of the display panel. The difference between Peak (small highlights) and Sustained (full-screen brightness) is a key indicator of power and thermal management.
| Tier | Peak (10%) | Sustained (100%) | Black Level | Color Gamut | Bit Depth | Dimming Type |
|---|---|---|---|---|---|---|
| LCD-Based Standards | ||||||
| DisplayHDR 400 | 400 nits | 320 nits | ≤ 0.4 cd/m² | 95% sRGB | 8-bit | Global dimming |
| DisplayHDR 600 | 600 nits | 350 nits | ≤ 0.1 cd/m² | 90% DCI-P3 | 10-bit (8+FRC) | Edge-lit / FALD |
| DisplayHDR 1000 | 1000 nits | 600 nits | ≤ 0.05 cd/m² | 90% DCI-P3 | 10-bit (8+FRC) | Full-array (FALD) |
| DisplayHDR 1400 | 1400 nits | 900 nits | ≤ 0.02 cd/m² | 90% DCI-P3 | 10-bit (8+FRC) | Full-array (FALD) |
| OLED-Based (True Black) Standards | ||||||
| True Black 400 | 400 nits | ~250 nits* | ≤ 0.0005 cd/m² | 95% DCI-P3 | 10-bit (8+FRC) | Pixel-level |
| True Black 500 | 500 nits | ~250 nits* | ≤ 0.0005 cd/m² | 95% DCI-P3 | 10-bit (8+FRC) | Pixel-level |
| True Black 600 | 600 nits | ~250 nits* | ≤ 0.0005 cd/m² | 95% DCI-P3 | 10-bit (8+FRC) | Pixel-level |
| *Note: OLED sustained brightness is lower to prevent burn-in; however, the perfect black levels maintain high perceived contrast. | ||||||
- Hardware Definitions
- Sustained Luminance: The maximum brightness held across the entire screen (100% white) for 30 minutes. Crucial for consistent image quality in bright scenes.
- Bit Depth: HDR requires at least 10-bit (1.07 billion colors) to prevent "banding." Most "10-bit" consumer monitors use **8-bit + FRC** (Frame Rate Control) to simulate this.
- Color Gamut: DCI-P3 is the cinema standard; it is significantly wider than the older **sRGB** office standard.
HDR Content Formats (Software)
[edit | edit source]While VESA defines hardware, these formats define how the digital signal is encoded.
| Format | Metadata Type | Max Potential | Color Depth | Description |
|---|---|---|---|---|
| HDR10 | Static | 1,000 nits | 10-bit | Baseline standard; one brightness setting for the whole video. |
| HDR10+ | Dynamic | 4,000 nits | 10-bit | Open standard (Samsung); adjusts brightness frame-by-frame. |
| Dolby Vision | Dynamic | 10,000 nits | 12-bit | Proprietary/Advanced; adjusts brightness scene-by-scene. |
| HLG | None | Variable | 10-bit | Used for live TV; compatible with both SDR and HDR sets. |
- Format Definitions
- Static Metadata: The display sets one "average" brightness for the whole movie. This can cause dark scenes to look too dark or bright scenes to lose detail.
- Dynamic Metadata: The display adjusts its brightness range for every single frame or scene, ensuring optimal detail in both dark and bright sequences.
- 8-bit + FRC: A temporal dithering technique used by many "10-bit" monitors to simulate 1.07 billion colors using an 8-bit panel.
External links for HDR
[edit | edit source]HDR with CRT Shaders
[edit | edit source]Inverse tone mapping
[edit | edit source]Unfortunately, most content we used in the past and today are SDR. While technology is improving, SDR contents can't natively showcase the entire spectrum of light information present in HDR display. But at least there is a way to potentially enhancing the visual experience for non-HDR content, this is where ITM comes into play. Inverse tone mapping is a post-processing technique that takes SDR content and expands its limited brightness and color range to approximate HDR.
- How It Works:
- The game (originally rendered in SDR) produces an image with a narrow dynamic range.
- NVIDIA RTX HDR analyzes this SDR output and applies inverse tone mapping, “guessing” what an HDR version might look like by stretching the brightness and color data.
- The result is sent to an HDR display, offering improved contrast and vibrancy compared to the original SDR output.
Tools
[edit | edit source]- Windows Auto HDR (Built-in Windows feature, similar to equivalent in Xbox One X|S and Xbox Series X|S)
- Special K: HDR Retrofit
- Machine-learning based NvTrueHDR, new NVIDIA app[5] is now available with the new Freestyle filter option called RTX HDR, See Shaders and filters#AI-powered filters.
Alternative tools
[edit | edit source]- Some of the standalone emulators comes with enhancement post-processing option for HDR such as Dolphin emulator[6][7][8].
- ReShade shaders such as EndlesslyFlowering's ReShade HDR shaders and PPFX Bloom.
- There are some shader presets for HDR displays or non-HDR but high-dim displays.
- NVIDIA RTX Video HDR: Enhancing SDR videos with AI-Powered HDR Conversion.[9]