What is luminance and chromaticity?

Luminance: Luminance is apparent brightness, how bright an object appears to the human eye. So when you look at the world what you see is a pattern of varying luminances (if we ignore the color component). What you see on the this page you are reading is the luminance of the black letters compared to the luminance of the white screen.

Luminance is measured in candelas per square meter.
Since luminance is what we see then light sources which we look at have luminance too. The luminance of the sun and the moon give us a good idea of the huge range of brightness which the human eye can handle.

Luminance of the sun: 1,600,000,000 cd/m2.

Luminance of the moon: 2500 cd/m2.

If you look at the sun you'll get 1,600 million candles per square meter into you eye. That is why you should not look directly at the sun for very long.

Chromaticity:

Chromaticity is an objective specification of the quality of a color regardless of its luminance. Chromaticity consists of two independent parameters, often specified as hue (h) and colorfulness (s), where the latter is alternatively called saturation, chroma, intensity,[1] or excitation purity.[2][3] This number of parameters follows from trichromacy of vision of most humans, which is assumed by most models in color science.

If You want to learn about the technology, computer science & engineering, web programming, freelancing, earning please click here :CSE SOLVE