ABSTRACT
In this chapter, the authors discuss the science of light, more commonly termed as radiometry. They describe different radiometric quantities and how they are used in the domain of visual computing. The authors describes how radiometry leads to photometry which is the science of light in the context of the human visual system and hence human perception. In radiometry light is considered to be a travelling form of energy and therefore the unit used to describe it is the SI unit of energy, joule. Using the aforementioned equations, they can write a simple light transport equation that defines how light is transported via surfaces or objects in the presence of lights from many different directions. The visible light spectrum has wavelength that varies between 400 nm and 700 nm. The sunlight is close to achromatic in the day time. Most of the manmade and natural colour stimuli are smooth spectra of polychromatic light.
