In "The Masque of the Red Death," do you think the imagery enhances your understanding of the story?

Absolutely, the imagery enhances the meaning of the story and, therefore, a reader's understanding of it.  The imagery concerning the seven rooms of the abbey where Prince Prospero and his friends hide from the Red Death is particularly rich.  In order from east to west, the rooms are draped in blue, then purple, then green, orange, white, violent, and, finally, black and "blood" red.  Because these rooms are ordered from east to west, the direction from which the sun rises and the direction in which it set, they could be understood to symbolize the span of a human life (just as the space of a day does: sunrise = birth, sunset = death).  

Further, the idea that death is represented by the final room of black and red is supported by the symbolism of the ebony clock.  Black is often used to represent death (as is red in this story, since the plague's "Avatar and its seal [is] the redness and the horror of blood), and clocks are also often symbols of mortality.  The fact that the revelers avoid the final room and seem especially anxious about the clock reinforces the idea that they fear death.  However, the relentless ticking of the clock confirms that the notion that death is coming, that it is unavoidable (no matter how rich or lucky someone is).  Thematically, all of this imagery and symbolism point to the idea that death is a part of life, and it is universal.  The prince may believe that his money and youth and health can protect him, but it cannot.