To find the coordinates of vertex D' after a dilation with respect to the origin using a magnitude of 1/2, we need to multiply the coordinates of vertex D by the dilation factor.
The coordinates of vertex D are (2, -2).
Applying the dilation:
\[ D' = \left( \frac{1}{2} \cdot 2, \frac{1}{2} \cdot -2 \right) \]
Calculating this gives:
\[ D' = (1, -1) \]
Therefore, the coordinates of vertex D' are (1, -1).
So, the answer is:
(1, -1)