ABSTRACT
This chapter introduces the fundamentals of colour description, measurement, evaluation and appearance. Knowledge of theories and current practices related to these topics is paramount in comprehending how colour is recorded, reproduced and managed in imaging media. Colourfulness denotes the extent to which the hue is apparent. Colourfulness is therefore zero for achromatic colours, low for pastel colours, high for oil paints and very high for spectral colours. For most luminance levels, the perceived colourfulness increases with increased luminance. Lightness is defined as the brightness of an area judged in proportion to the brightness of a similarly illuminated area that appears to be white. The interaction of electromagnetic energy with objects is not merely a spectral phenomenon but depends also on the viewing angle of the observer with respect to the object, as well as the illumination angle the illumination and geometry.
