How does Charlotte Perkins Gilman use imagery in The Yellow Wallpaper?

Imagery:

"All those strangled heads and bulbous eyes and waddling fungus growths just shriek with derision!..."

"I can see a strange, provoking, formless sort of figure, that seems to skulk about behind that silly and conspicuous front design...."

"The color is repellent, almost revolting; a smouldering unclean yellow, strangely faded by the slow-turning sunlight...."