This directional blur is really lighter and make softer blur also than the native DirBlurWrapper .
Channels: To choose on witch channel the blur will be apply.
Angle: To choose the direction of the blur.
Angle Preview: Draw a line to easely adjust the direction.
Center: Adjust the center to move the line if it is necessary.
Blur Lenght: To define the blur size.
Crop to Format: To keep the input bbox format.
I made this one with my colleague Gaetan Baldy.