Pigments are substances that have an ability to absorb light, at specific wavelengths.
The colour of the leaves is due to four pigments such as
Chlorophyll a (bright or blue green in the chromatogram),
chlorophyll b (yellow green),
xanthophylls (yellow) and
carotenoids (yellow to yellow-orange)
The wavelengths at which there is maximum absorption by chlorophyll a, show higher rate of photosynthesis; hence, we can conclude that chlorophyll a is the chief pigment associated with photosynthesis.
Other thylakoid pigments, like chlorophyll b, xanthophylls and carotenoids, which are called accessory pigments, also absorb light and transfer the energy to chlorophyll a, and also protect chlorophyll a from photo-oxidation.