CAM16

CAM16 is a color appearance model introduced to describe how colors are perceived under varying viewing conditions. It was developed as an advancement over prior models such as CAM02 and CIECAM02, aiming to improve perceptual uniformity and the accuracy of color appearance predictions across a wide range of illuminants, adaptations, and surroundings. The model is designed for color management, image processing, and color rendering tasks in digital imaging pipelines, where accurate prediction of perceived color is important.

In CAM16, colors are represented in a perceptual space using attributes such as lightness (J), chroma (C), and hue angle (h). A related, perceptually uniform space called CAM16-UCS provides coordinates that enable more intuitive color difference measurements, analogous to how ΔE measures are used in other color spaces. The forward CAM16 transform converts scene-referred tristimulus values (for example, XYZ) into appearance attributes, taking into account the viewing conditions, including the adapting field, surround, and white point. The model incorporates chromatic adaptation and nonlinear responses to better reflect human visual processing. The inverse transform maps appearance attributes back to a tristimulus representation, enabling color rendition or rendering under desired conditions.

A key feature of CAM16 is its explicit treatment of viewing conditions, including a surround factor and adaptation level, which influence perceived brightness, colorfulness, and hue appearance. This makes CAM16 suitable for color management workflows that need to predict how colors will look under different lighting environments.

Applications include color difference assessment, image and video editing, display calibration, and color grading. Limitations involve computational complexity and the need for accurate input about viewing conditions. While implemented in some color science libraries and tools, CAM16 is less ubiquitous than older models in commercial ICC workflows.