High Dynamic Range

This page explains how HDR works on DSOS 4.9.x, how to prepare HDR content, and how to verify that your iBX440 is outputting HDR correctly.

Overview

High Dynamic Range (HDR) is a technology used in imaging and display devices to enhance the contrast and color range of the visuals.

Key aspects:

Enhanced Contrast: HDR increases the difference between the darkest and brightest parts of an image, resulting in brighter highlights without clipping, deeper shadows, and more detail across the entire brightness spectrum.
Wide Color Gamut (WCG): HDR can display a broader range of colors – more saturated tones, more vivid oranges, reds, greens, and purples, better reproduction of real‑world materials (skin tones, neon lights, etc.) – making images look more vibrant and realistic.
Brightness: HDR content can achieve higher brightness levels, which helps in displaying more details in bright areas without washing out the image.
HDR Formats: Common HDR ecosystems include HDR10, Dolby Vision, and HLG (Hybrid Log-Gamma); each format has its own specifications and advantages. On iBX440 / DSOS 4.9.x, HDR output support is based on PQ (Perceptual Quantizer / ST.2084) and HLG workflows.

HDR is commonly used in TVs, monitors, cameras, and streaming services to provide a more immersive and lifelike viewing experience. HDR content can be encoded using various codecs (like H.265) and stored in different formats (like MP4 or MKV).

When should you use HDR?

Use HDR when the full playback chain supports it: HDR content, Elementi HDR project, an iBX440 player, a compatible cable, and an HDR-capable display. If any part of the chain is SDR-only, the player falls back to SDR output and tone mapping is applied where needed.

HDR/WCG support

DSOS 4.9.0 / Elementi 2025 introduces the support for High Dynamic Range (HDR) and Wide Color Gamut (WCG) output on iBX440 players, enabling brighter highlights, deeper shadows, richer color reproduction, and an overall more lifelike visual experience on compatible displays.

HDR support includes:

10‑bit and 12‑bit internal pipelines
PQ (ST.2084), HLG, and gamma transfer functions
10‑bit/12‑bit color depth HEVC (H.265) and AV1 and the full H.273 color parameters for video files
AV1 Image File Format (AVIF) and ICC profiles in PNG and JPEG images for wide-gamut color support
Automatic HDR mode selection based on display's EDID
Advanced tone mapping for SDR fallback
New HDR-related parameters in Elementi 2025 for content authors. HDR is enabled per project.
Rec. 2100 – ITU-R Recommendation for HDR-TV (same chromaticity of color primaries and white point as Rec. 2020 with PQ or HLG)

Wide Color Gamut support includes:

Rec. 2020 – ITU-R Recommendation for UHDTV
DCI-P3

HDR is enabled through a project setting. Once the Elementi project is published, the player automatically switches the rendering pipeline to high‑precision, and enables HDR video output mode if the connected display supports HDR. If the connected display does not support HDR, content is tone-mapped to SDR.

Requirements

To benefit from HDR, you need:

Hardware:

iBX440 player
HDR-capable display supporting HDR10 and/or HLG
HDMI 2.0 or DisplayPort connection
Cable rated for the required resolution, refresh rate, and 10/12-bit color depth.

Note that the iBX440 does not support HDMI 2.1, so HDR in 4K resolution on HDMI will use 4:2:0 subsampling.

Software:

DSOS 4.9.0 or later
Elementi 2025 or later
Elementi project explicitly configured as HDR

HDR content:

HDR video content encoded as 10‑bit or 12‑bit HEVC/H.265 or AV1
High‑quality HDR/WCG images such as AVIF, PNG, or JPEG with appropriate color information where supported

HDR content can be published to an iBX440 connected to an SDR screen and will gracefully tone map, but HDR content cannot be published to non-8K capable players such as the iBX410 or HMP400.

HDR projects in Elementi

Create an HDR project

Follow these steps:

Create a new project in Elementi.
Make sure to set the following project's properties within the "New Project" dialog:
- Model: Select the target player model as "iBX440 / 8K Partner Player".
- Color Gamut: Select HDR.
- HDR Mode: Select from HLG, PQ, and Gamma. This defines which transfer function is used to drive the HDR output of the player.
- White level: Enter the diffuse white luminance; defaults to 400lm (in the current UI). This defines the reference brightness for “normal” white surfaces in the image (e.g. paper, walls, skin tones).
- Max CLL: Enter the maximum pixel brightness the content is expected to reach. Defaults to 1000lm(in the current UI).
- Max FALL: Enter the maximum average brightness of an entire frame to avoid sustained over‑brightness. Defaults to 1000lm (in the current UI).
Click the 🆗 button to create the project.

Notes:

Elementi does not render the content in HDR, it uses tone mapping.
The default values of the brightness parameters are wrongly labeled as lumens (lm), instead of nits (cd/m²). This will be fixed in the next release.
To revert a project to SDR, change the color gamut to SDR in project settings. Be aware that any HDR media must be removed or replaced by an SDR equivalent in this case.

HDR mode and brightness parameters

When creating an HDR project in Elementi, the “HDR Mode” setting defines the transfer function used by the rendering pipeline and determines how the HDR-related brightness parameters (“White level”, “Max CLL”, and “Max FALL”) are interpreted. The available modes are “PQ”, “HLG”, and “Gamma”. PQ and HLG are HDR transfer functions; Gamma uses a traditional SDR-like brightness curve and is intended for WCG workflows where extra brightness is not required. Not all parameters apply to all modes.

Which HDR mode should I choose?

Use HLG for most signage projects and installations where display characteristics may vary.
Use PQ when working with properly mastered HDR10 content and controlled display environments.
Use Gamma when HDR output is not required or when targeting SDR displays only.

HLG

HLG (Hybrid Log‑Gamma) is a relative HDR mode that adapts automatically to the brightness capabilities of the display. It is recommended for signage and installations with varying or unknown display brightness.

In HLG mode:

White level is the primary brightness control
MaxCLL is treated as a guidance value for highlight roll‑off
MaxFALL acts as a soft limiter

PQ

PQ (Perceptual Quantizer – ST.2084) is an absolute HDR mode where signal values correspond to real‑world luminance (in nits). It is recommended for properly mastered HDR10 content and controlled display environments.

In PQ mode, all parameters are fully active and used for tone mapping:

White level sets the reference white luminance
MaxCLL defines the expected peak highlight brightness
MaxFALL limits sustained average brightness

Gamma

Gamma corresponds to a traditional SDR-like transfer function. It is used for WCG workflows where extra brightness is not required as it maximizes the usage of the 10 bits for color range. In this mode:

Brightness behaves as SDR
White level maps to standard SDR white
MaxCLL and MaxFALL are disabled
The player requests an output mode suitable to display the wider color gamut, if supported by the display

White level

This defines the reference brightness for “normal” white surfaces (e.g. paper, walls, skin tones). It primarily affects mid‑tones, not peak highlights.

Lower values → darker mid‑tones, stronger highlight contrast
Higher values → brighter overall image, flatter highlights

Diffuse White is active in PQ and HLG modes.

Max CLL and Max FALL

Max CLL (Maximum Content Light Level) specifies the maximum pixel brightness the content is expected to reach.
Max FALL (Maximum Frame‑Average Light Level) limits the maximum average brightness of an entire frame to avoid sustained over‑brightness.

If the display is HDR capable, the Max CLL, Max FALL, and color primaries values are sent to the display as static metadata (e.g., HDMI info frames). The player does not control how the display uses this information but it is typically used for internal tone mapping because most displays have relatively limited true HDR ranges compared to the full PQ and HLG curves.

When the display is not HDR-capable, these parameters are used by the player to perform tone mapping of HDR media to SDR range.

While the player will consume static (HDR10) or dynamic (HDR10+) metadata in video files, if present, to perform optimal tone mapping when it does tone mapping, the values sent to the display in info frames are the static ones you configure for a project since a scene may be composed with multiple medias, each having its own metadata. The Max CLL and Max FALL in this case are your "mastering" values and rendering on screen will be optimal when these values closely match the actual characteristics of the display.

Note:

Elementi’s default Max CLL and Max FALL values are intended to provide reasonable general-purpose settings for typical HDR signage content. Max CLL and Max FALL should describe the expected brightness characteristics of the project. Higher values are not necessarily better. If these values are set significantly above the actual content brightness or display capability, the display or tone-mapping algorithm may preserve excessive highlight headroom, resulting in a darker or less contrasted image. Avoid using very high values, such as 10000 cd/m², unless the content was specifically mastered for that peak brightness and the target display chain is designed for it.

Use HDR content

If target hardware supports HDR, then HDR is preserved fully end‑to‑end upon import; HDR metadata (primaries, transfer function, mastering info) is preserved to ensure correct output. All elements are rendered in high precision to minimize banding.

Supported formats:

Video: 10‑bit/12‑bit color depth HEVC (H.265) and AV1. Very heavy formats (e.g., 8K60 HDR AV1) may be transcoded automatically for stable playback.
Graphics: AV1 Image File Format (AVIF), PNG, JPEG, and other standard formats with wide-gamut color support

If the target is SDR‑only, then Elementi applies tone mapping and resulting media becomes SDR-safe. Elementi shows a warning whenever tone mapping has been applied.

Use standard content

Non-HDR assets can be used in HDR projects:

Existing templates, widgets, SVGs, CSS colors
Standard sRGB colors remain visually consistent
The HDR pipeline reduces banding and improves gradients

Use WCG Colors

Standard CSS colors work normally. For wide-gamut colors, use:

color(display-p3 r g b)
color(rec2020 r g b)

Values for red, green, and blue are typically represented as decimals from 0 to 1.

iBX440 player behavior

When playing an HDR project, the iBX440:

Reads the display's EDID.
Detects HDR/WCG support.
Selects HDR10 or HLG mode (10/12‑bit, RGB/YCbCr as appropriate).
If unsupported, falls back to SDR and tone maps content.

The player reacts to display hot-plug events as usual, just that after each event, the player recalculates HDR capability and re-applies the correct output mode.

Diagnostics and verification

HDR output status

When verifying the HDR output, check for:

HDR output mode: active / inactive
Transfer function: PQ or HLG
Bit depth: 10-bit or 12-bit
Color format: RGB 4:4:4 or YCbCr 4:2:0

This information can be found through the Status API's info endpoint (XML format) or the get_info RPC command (JSON format) – if HDR output is enabled, an <hdr> element is present under <screen> <display> <mode> for the former, respectively an hdr property is present under display.mode object for the latter.

Troubleshooting Checklist

If HDR output is not active:

Check that the display advertises HDR10 or HLG support.
Confirm that the player is an iBX440 running DSOS 4.9.0 or later.
Verify that the project is marked as HDR in Elementi.
Verify the HDMI / DisplayPort cable and input port support the required resolution and bit depth.
Check the HDR output status, as detailed above.
Check the display-reported HDR capability from EDID in player.log.
Test with a known-good HDR project and HDR video file.

Snapshots

The iBX440 supports:

JPEG snapshots with embedded ICC profile, available in Control Center and via the Status API.
16‑bit PNG snapshots for diagnostics (gradients, tone mapping evaluation) via the Pull Mode's upload action – to get a PNG file, use -snapshot shortcut followed by a destination file name with a .png extension.

These help in comparing displays, tuning HDR parameters, or sharing issues with support.

Multiscreen considerations & limitations

Mixed HDR + SDR video walls may not behave predictably – to be avoided.
Systems may fall back to SDR if common capability is not found
Some hardware generations show slight variations in very bright highlights

Best Practices

Use HDR sources, HDR projects, HDR players, HDR displays — end‑to‑end HDR pipeline
Adjust HDR parameters (White level, Max CLL) while viewing the final display
Confirm output state via Status or snapshots
Test on the target hardware — ambient light and display quality strongly affect perceived HDR impact