Mirror--AE

This effect splits the image along a line and reflects one side onto the other. The reflection angle determines which side is reflected and where the reflection appears. You can make the line and reflection angle change over time.

Reflection Center Specifies the position of the line. Click the box and drag the resulting cross hair to the spot in the image where you want to place the line.

Reflection Angle Specifies the angle of reflection, and therefore where the reflection appears on the clip. An angle of 0 degrees reflects the left side on the right. An angle of 180 degrees reflects the right side on the left. An angle of 90 degrees reflects the top on the bottom. An angle of 270 degrees reflects the bottom on the top.

Applying Effects > Video effects included with Premiere > Mirror--AE