How does the author use imagery in the novel, Tackle Without a Team?

Imagery:

Red and gray uniforms, most of them still clean and unsmudged, and matching helmets flashed before Scott Kramer's eyes as he crouched down, dug his toes into the turf in his right tackle spot, and faced the tackle in front of him. Left tackle Joe Salerno's eyes, peering through his metal face mask, were like two dark, white-rimmed holes. pg. 3

"Brace up, Kramer." Joe's low-pitched remark sounded like a snarl.

The ball was snapped. Both teams rushed toward each other across the scrimmage line. Helmets and shoulder pads clashed, breaths heaved. pg. 4