Local Direction Detector is used in video processing to estimate the direction of an edge or texture element for an individual pixel.
One directional detection method estimates the value of pure vertical or horizontal direction with respect to diagonal “north-west to south-east” or diagonal “north-east to south-west” directions. This method is based on measuring the high frequency energy E1 in “north-west to south-east” direction and the high frequency energy E2 in “north-east to south-west” direction.
The estimated value of the angle is equal to the arctangent of the ratio E1/E2. Usually the particular application using the estimated direction, such as a directional interpolator, requires a mapping of the angle by a nonlinear function.