Median Filter Functions

Median filters are nonlinear rank-order filters based on replacing each element of the source vector with the median value, taken over the fixed neighborhood (mask) of the processed element. These filters are extensively used in image and signal processing applications. Median filtering removes impulsive noise, while keeping the signal blurring to the minimum. Typically mask size (or window width) is set to odd value which ensures simple function implementation and low output signal bias. In the Intel IPP median function implementation, the mask is always centered at the input element for which the median value is computed. You can use an even mask size in function calls as well, but internally it will be changed to odd by subtracting 1. Another specific feature of the median function implementation in Intel IPP is that elements outside the source vector, which are needed to determine the median value for “border” elements, are set to be equal to the corresponding edge element of the source vector.