Summary: Given integer values for red, green, and blue, subtract the gray from each value.

Computers represent color by combining the sub$-$colors red, green, and blue $($rgb$).$ Each sub$-$color's value can range from $0$ to $255.$ Thus $(255,0,0)$ is bright red, $(130,0,130)$ is a medium purple, $(0,0,0)$ is black, $(255,255,255)$ is white, and $(40,40,40)$ is a dark gray. $(130,50,130)$ is a faded purple, due to the $(50,50,50)$ gray part. $($In other words, equal amounts of red, green, blue yield gray$).$ C$++$