Zoom in/out transition in Blender
Directional Blur is a feature of the VSE (video sequence editor), aka compositor.  When you open up Blender, select Video Editing as the Screen Layout.  Make one window a Node Editor (where you will introduce your directional blur node), and choose the Compositing view. Open another window as a Video Sequence Editor (where you will put your clips) and view it as a Sequence.  Then, either enable Backdrop in the Node Editor (so you can see your rendered result) or open a third window as a UV/Image Editor displaying Rendered Result.  You might have to set your render resolution to get 100% of your image (because the default is to render at 50% resolution, and while that just shrinks things for 3D worlds, it crops things for the compositor).

At the first frame, set the number of iterations to 1 and set a keyframe (right click).  Set the zoom factor to 0 and set a keyframe.  At the last frame, set the zoom to 1.0 or 2.0 or whatever you consider to be a maximum.  Tune up the number of iterations to whatever makes it smooth (could be 10, 20, whatever).  Keyframe those.

With your second clip (that you are zooming to), set the first frame of the effect to the same zoom and iteration numbers that you used for the last frame of your first clip.  Keyframe those.  For the last frame of the effect, set the iteration count to 1 and the zoom amount to 0.0 and keyframe those.  Then cross fade between the two.

In the middle you should have two very zoomed images that, when blended 50/50, look like they could logically belong to either image (because it's mostly just blurred pixels).

The above was checked with the latest release of Blender: 2.79b.