What is Tone Mapping / ACES (ACEScg)?

Definition of Tone Mapping / ACES (ACEScg)

Tone mapping translates "scene-referred" renders with a wide dynamic range into the "display-referred" range of a target display (sRGB/Rec.709/HDR) so that contrasts, colors and highlights appear natural. ACES (ACEScg) is an open color space and pipeline system that standardizes this translation - from input (IDT) to render (ACEScg) to output (ODT). Here we show how we use ACES in realistic fire renderings: 3D Fireplace & Stove Rendering.

For consistent material responses, please also refer to PBR – Physically Based Rendering.

Why tone mapping & ACES are crucial for brand images

• Consistency Across Channels: Catalog stills, social media clips, product videos, web viewers—with ACES, the visual style remains consistent. This is how we maintain the same look from stills to video: 3D product video – modular furniture.
• A natural sense of light: Highlights don’t clip harshly, and shadows aren’t as dark—rooms and products look photorealistic.
• Team Scaling: A Consistent Color Space Prevents Correction Loops Between DCC, Grading, and 3D Render Studio.

Basics: Scene- vs. display-referred, ACEScg & ODT

• Scene-referred: linear render values with a wide dynamic range (e.g., ACEScg).
• Display-referred: what a specific display is capable of displaying (sRGB/Rec.709, HDR formats).
• IDT/ODT/RRT: ACES defines Input Device Transform, Output Device Transform, and a Reference Response Curve (RRT) to ensure reproducible results. Further reading: a concise overview from the Academy (ACES) → Academy Color Encoding System – Overview.

Comparison Table: ACES vs. “Standard sRGB” vs. “Filmic”

For color management in DCC/grading, we recommend ACES integration via OpenColorIO → OpenColorIO – Using ACES Config.

Practical workflow (7 steps) - robust for interior & product

1. Set references: CI-Mood, target display (sRGB/Rec.709 or HDR).
2. Set the renderer to "scene-referred": perform internal calculations in ACEScg, and create materials in the PBR sense (albedo without light).
3. Select IDT: Correctly import source material (e.g., texture photography) into the scene.
4. Setting light: physically plausible sources + HDRI / Image-Based Lighting for natural ambient light. Interior lighting design in practice: Virtual bathroom design - Canyon House. We show how we use warm flame light with GI and glass reflections for branded products in the 3D fireplace & stove rendering.
5. Transform ODT/Viewing: Define the target display (e.g., Rec. 709-ODT); do not apply "gamma-n" twice to intermediate steps.
6. QA & dailies: comparison with material samples; clean handover points for video playout 3D animation & product video.
7. Delivery & Variants: Stills for 3D product visualizationinteractive assets in 3D viewer (note sRGB display there again). Brand space with consistent ACES display: Interactive brand spaces - FOR Home Haus 2025.

Common errors & quick fixes

FAQ - Tone Mapping / ACES (ACEScg)

What is tone mapping, and why do I need ACES?

Tone mapping adapts renders with a high dynamic range to the display's range so that contrasts appear natural. ACES provides a standardized pipeline for this purpose, ensuring that visual styles remain consistent across tools and output channels.

What is the difference between ACES and ACEScg?

ACES is the overall system (color spaces, transforms). ACEScg is the linear working color space for rendering and compositing (scene-referred); the output is then sent via ODT to the target display (e.g., sRGB/Rec.709).

What do IDT, RRT, and ODT stand for?

IDT (Input Device Transform) correctly maps sources into the scene color space; RRT is the reference tone curve; and ODT (Output Device Transform) maps the result to the target display. Together, they ensure reproducible colors and contrasts.

Why do renders look different on the web than they do in DCC software?

Because browsers expect sRGB displays. Export using the appropriate ODT/conversion to sRGB and disable any additional viewer tone curves; otherwise, you'll unintentionally add a second curve.

How can I avoid the most common mistake—"double tone curve"?

Keep only one viewing transform active (e.g., ACES ODT), do not apply any additional "Auto-Contrast/Gamma" during export, and disable any additional look operators in the target tool (browser/player).

When is ACES worth it—and when is sRGB/Filmic enough?

ACES is worth using for series, moving images, multi-team pipelines, and cross-channel CI visual language. For quick individual stills or previews, an sRGB/Filmic setup may suffice—but as soon as multiple releases are planned, ACES saves time and reduces the need for corrections.