Look at the visual in the 2010 VCAA English exam available at

Effect on reader

Images may often be cropped to only include part of the overall picture. Sometimes this can be used to create meaning by what is included or excluded from the image that is actually presented.

In the example of the 2010 VCAA exam, the visual includes a pair of hands, signifying to the reader that a human is part of the visual, and yet the person’s face and body is excluded from the image. This is effective in leaving the owner of the pair of hand’s identity ambiguous; allowing the reader to see the hands as representing all of mankind. It could also be interpreted as indicating that the pair of hands could belong to anyone- including the reader- putting responsibility on them to care for the planet.