The images created in the poem help to illuminate world of denial and the inaction of dreams. The idea of the shriveled up raisin in the blistering sun helps to expose the reader to a mental picture of continual disrespect and denial of one's hopes and vision of a future. "Fester like a sore" helps to evoke the idea of a wound that never is able to fully heal, helping to being to light the idea that there is a defined level of personal pain experienced with the deferral of dreams. "Stink like rotten meat" continues to utilize sensory images in articulating a vision of the world where pain and despair rule supreme, only this image sees the externalization of these elements. The notion of using mental pictures to help bring out these ideas is one where individuals are able to understand the reality of dreams denied and those that perish under the weight of what is.
Langston Hughes' short poem "Harlem" is pretty much successful because of its imagery. Take away the imagery and you have nothing left aside from the opening question, "What happens to a dream deferred?". The poem has five or six images. The first five images are very clearly and concretely presented in more than five words and often in combination with a simile (the poem makes repeated use of comparisons using the word "like"): "a raisin in the sun," a festering "sore," "rotten meat," "a syrupy sweet," and "a heavy load." The final line of the poem -- "Or does it explode?" -- might be considered to include an image and a comparison, too, but these elements are much less developed in the final line than they are earlier in the poem.
On a side note, the first image is the most famous of the bunch and provided Lorraine Hansberry with a title for her widely read play on urban Afircan American life in the mid-20th century.