To create Polar effect, click Deformation | Polar or select Polar folder.
By Choosing Inverse, you can flip the image referring to the vertical line of symmetry.
By Choosing Backwards, you can flip the image referring to the horizontal line of symmetry.
By Changing the Angle value you can turn the image on given angle.
By Sliding the Value scroll box you are squeezing the image from the corners toward the center.
This effect gives a view of the image as if you are standing on the on North Pole and looking down.