Color consistency for e-commerce – display every day

Reliable, repeatable color mapping has always been a problem because there are too many uncontrollable variables in the pipeline, one of which is the color LUT settings on all the displays involved. Avoiding this elephant in the room, Khronos made a significant contribution by standardizing color tone values. Adoption will take time and may never happen for some consumers, but for those who care about what the sofa they can buy actually looks like, it will be a godsend.

Khronos MapsColors according to the established standard

Khronos has released the specifications and sample implementation of PBR Neutral Tone Mapper, a new tool designed to ensure accurate and faithful reproduction of 3D assets rendered using physically-based rendering (PBR). This solution is tailored to applications such as e-commerce, architecture and CAD where realistic colors are paramount.

Khronos says the tone mapping tool has already gained widespread adoption and support from leading 3D tools and engines, including Autodesk, Babylon.js, Blender, Dassault, Filament, London Dynamics, Phasmatic, Three.js and Threekit.

This tone mapping module is designed to eliminate HDR artifacts and ensure that the product’s underlying color, hue and saturation are accurately reproduced in grayscale lighting. It complements existing tone mapping tools such as ACES that are geared towards other types of content or artistic stylings.

According to Khronos, artists can be confident that their PBR-based renderers will faithfully reproduce the desired colors without the need for complex procedures and tedious manual adjustments. According to the organization, the specification is extremely simple to implement and contains only 13 lines of OpenGL Shading Language (GLSL) code. It also supports analytical inversion of tone mapping functions.

Initially developed to support workflows in the glTF 3D asset format, Khronos PBR Neutral Tone Mapper is file format agnostic and currently supports output to sRGB, with plans to expand support for additional outputs in future releases. Additionally, Khronos is exploring future glTF exposure controls to enable precise setting of actual lighting values ​​that are necessary for accurate color display.

Using a conventional post-processing technique that simulates film’s response to light by mimicking the film’s tone curve in images, film tone mapping tools such as ACES present a challenge when rendering realistic assets, particularly due to the limited range of achievable colors. Light shades such as yellow, green or cyan may not be reproduced faithfully on standard sRGB displays, leading to a blurry appearance of 3D objects. Artists often avoid the tone mapping tool altogether to alleviate this problem, which can increase saturation but can cause problems such as hue distortion, visual anomalies, or reduced dimensionality, especially on reflective surfaces.

Khronos says its PBR neutral tone mapper is designed to achieve precise 1:1 color matching up to a specified maximum value, reserving the remaining space for compressed highlights. This approach allows content creators to maintain the integrity of primary colors, textures, and dimensions.

The attached diagram visually compares the achievable colors for Khronos PBR Neutral with the commonly used ACES film tone mapper. The cube represents the space (0, 1) in linear light without using the sRGB curve. This visual highlights the unique color retention capabilities of Khronos PBR Neutral Tone Mapper.

Khronos PBR Neutral Tone Mapper gives artists a new option to create assets tailored to their application needs. Neutral, Linear and Cinematic Tone Mapping Khronos PBR has various applications and benefits:

• Linear tone mapping (i.e. “no tone mapper”) works well for models without HDR input and physical lighting.
• Film tone mapping (e.g. ACES, AgX) should be used in highly HDR scenes, in applications with a wide range of input colors, or to achieve a specific artistic look.
• Khronos PBR Neutral is designed for physics-based photorealistic rendering with well-exposed scenes, accurate reproduction of sRGB primary colors in grayscale lighting, and unbiased reproduction in colored light such as sunlight.

Taking the guesswork out of content creation

Khronos PBR Neutral Tone Mapper allows you to verify the primary color of a 3D object regardless of the lighting environment, which is a win-win solution for artists, brands and end users. These benefits include:

• Less guesswork: Artists can verify color values ​​in a texture file; The “guess and check” process of building a model and testing colors in the final render has been eliminated.
• Shorter quality control cycles: There is less risk of color issues being found in the finished model, resulting in fewer reworks and delays.
• Faster updates: Object colors can be updated quickly and easily in the asset file, without the need for additional quality control.
• Flexibility: Marketing and graphic design professionals can change lighting to achieve the desired look without having to adjust the colors of the base model to maintain color accuracy.

The development and rapid implementation of Khronos PBR Neutral Tone Mapper was possible thanks to cross-industry cooperation that takes place within the Khronos 3D Formats and 3D Commerce working groups. We encourage content creators, artists, implementers, and engine developers to share their opinions, questions, and suggestions for future improvements by contacting the Working Group on GitHub, Discord, the Khronos Discussion Forum, Stack Overflow, or X.

Khronos has open-sourced the Khronos PBR Neutral specification and welcomes community feedback and suggestions for future improvements via the Khronos PBR Neutral Tone Mapper GitHub repository. We encourage content creators, artists, implementers, and engine developers to interactively test the sample implementation of Khronos PBR Neutral using their own assets and glTF lighting to determine if it is a good fit for their use case, and report feedback and issues on GitHub.

Dr. Jon Peddie is a recognized graphics industry pioneer, president of Jon Peddie Research, and one of the world’s most influential analysts. Jon is an ACM Distinguished Speaker and an IEEE Distinguished Visitor, as well as a named IEEE Computer Society Distinguished Contributor and Charter Member. He lectures at numerous conferences and universities on topics related to graphics technology and emerging trends in digital media technology.