What colors and imagery are used within the text? Why does the author choose to use these colors/images in Kaffir Boy?

In Kaffir Boy by Mark Mathabane dark colors and frightening imagery are often used in order to convey the terror under which the protagonist lives.

In the second chapter of the novel, the narrator describes his nightmares in which 

...throngs of black people sprawled dead in pools of red blood, surrounded by all sorts of slimy, creeping creatures. (Ch.2)

Then, in Chapter 3 as the children are terrorized by the assault of policemen outside the shacks, the brown of their uniforms and other mention of dark colors depict the threat of harm to the family. Another prominent image in this chapter is that of blinding light and blood as the policemen knock down doors and bludgeon some people. The protagonist is terrified as the policemen knock in the door to his family's shack:

As it swung wide open, two tall black policemen in stiff brown uniforms rushed in and blinded me with the glare from their flashlights. (Ch. 3)

The black and "red-necked" white policemen become a tormenting presence in the main character's life.

In several of the early chapters, the "flickering light of ...candle(s)" is mentioned. This repeated image suggests the glimmer of hope that will come for the narrator in the darkness. Amidst this light, however, the short, gaunt figure of his father looms. The boy describes his father as having fearsome features. Two of these features are 

...smooth, tight, black-as-coal skin...small bloodshot eyes which never cried. (Ch. 7)

Further, as the protagonist suffers terribly from hunger, he describes it using sensory imagery:

[Hunger was] in the empty pots, in the black children....At times it was the silent destroyer, creeping in unseen, unrecognized, except when, like a powerful time bomb, it would explode inside my guts. At other times it took the form of a dark, fangedbeast, and hovered constantly over my dizzy head, as if about to pounce... and gouge my guts out with its monstrous talons. (Ch. 10)

One night in the winter, with coals burning in order to warm the shack, the boy awakens, choking for breath. He feels

...as if two steel claws had locked themselves around my throat. (Ch.13) 

His mother explains that the fumes from the coal--"puffs of smoke coiled upward as raindrops fell on them"--have cut off her son's breath. (Ch.13)

In Chapter 17 he describes the stress under which he suffers,

O, my eyes were cloudy and my 
head pounded as if it were being split with an axe” (Ch.17)

This use of vivid and strong imagery conveys the brutal conditions and deprivation under which the protagonist lives, along with the struggles of his youth.