Most images are cropped down and this can change the entire meaning of an image and its effect upon the target audience.
Example - A photograph taken on 9/11. The image depicted in the first photograph is quite mundane as it appears to show an ordinary wealthy Western businessman reading his newspaper on a dirty street. Maybe the fact that the man is wearing a business suit connotes his position in society contrasted with the squalid street. The next photograph shows the entire disaster scene all around him. The debris of all the newspapers destroyed in the 9/11 catastrophe was one of the most iconic images created at the time. Symbolically, millions of sheets of burnt newspapers floated down from the windows of the twin towers. The new meaning of the photograph is the frailty of Western civilization as the Western business man is dwarfed by the chaos around him so he appears weak and helpless despite his power dressing. This is a startling contrast to the meaning of the first photograph.