A transformation of a geometric figure is a change in its position or size.  The original figure is the pre-image and the resulting figure is the imageAn example is shown below.

If the pre-image is labeled with letters, such as hexagon ABCDEF below, then the image is labeled with the same letters followed by a prime symbol, A'B'C'D'E'F'.

Pre and Image with letters

Each pre-image point, line, or angle maps its image onto a corresponding point, line or angle, respectively.  For example, in the hexagons above:

    • the image of point A is A'. 
    • the image of segment CD is segment C'D'.
    • the image of angle DEF is angle D'E'F'.

In other words, there is a one-to-one correspondence between the parts of the pre-image and its image.