A site dedicated to the Management of Light and Color in Lighting Design and Digital Color Applications. Here is a collection of easy-to-use, hands-on online Vision Tests, Color Calculation Tools, and prerelease versions of my books. It is also home to the CIE-JS WebAssembly Library, which implements colorimetric algorithms for colorimetry and digital color management applications.

CCT Calculator

To describe the color of white light, typically a correlated temperature and tint value are used, calculated through complex algorithms that rely on x and y chromaticity coordinates or X, Y, and Z tri-stimulus values. This easy-to-use tool implements a fast, high-accuracy bisectional search method based on Robertson’s algorithm.


Learn how good you are at discriminating colors with this app. It uses four colored quadrants, three of which are the same color and one with a slightly different hue. The test has six rounds, each with eight different hues. Your task is to click the quadrant that doesn’t match the others.

Illuminant Catalog

Access the library’s illuminant data, view spectral irradiance plots, chromaticity values, and Color Rendering Indices. Use this tool to familiarize yourself with different lamps’ spectral properties and color rendering characteristics. Copy spectral data into your device’s clipboard for use in other applications.

Munsell Color Books

Browse the Munsell color book samples by selecting a collection using the left tab and a color page on the right tab. The collections used here are kindly made available by the University of Eastern Finland and Robin Myers for free for educational purposes. Click on a sample to see measured spectral reflectivity values and chroma[…]