Brightness

Based on precise measurements of colour perception, some constructed detailed atlases, such as famous Munsell system (Albert Henry Munsell, 1898 / 1905). Yellow tends to appear lighter than others, such as blue. Some hues also tend to appear more vivid than others, such as magenta compared to turquoise.Within the spectrum, our eyes are more sensitive to medium wavelengths, which is why yellow appears brighter than indigo. Also, the intensity increases by a constant amount from one slice to the next. However, the variations seem stronger in the dark areas, than in the light areas. This is the Weber-Fechner law. We can model this effect with a mathematical function, , which represents our perception of brightness as a function of the actual physical luminance of the light.