Median Filter (G Dataflow)

Version:

Applies a median filter of rank to a signal.

Rank is right rank if right rank is greater than zero. Rank is left rank if right rank is less than zero.

signal

The input signal to filter.

The number of elements, n, in signal must be greater than right rank. If the number of elements in signal is less than or equal to right rank, the node sets filtered signal to an empty array and returns an error.

left rank

The number of elements used to compute the median filter to the left side.

left rank must be greater than or equal to 0.

Default: 2

right rank

The number of elements used to compute the median filter to the right side.

If right rank is less than 0, the node assumes right rank is equal to left rank. right rank must be less than signal.

Default: -1

error in

Error conditions that occur before this node runs. The node responds to this input according to standard error behavior.

Default: No error

filtered signal

Filtered signal.

error out

Error information. The node produces this output according to standard error behavior.

Algorithm Definition

This node obtains the elements of filtered signal using the following equation.

${Y}_{i}=\mathrm{Median}\left({J}_{i}\right)\text{\hspace{0.17em}}\mathrm{for}\text{\hspace{0.17em}}i=0,\text{\hspace{0.17em}}1,\text{\hspace{0.17em}}2,\text{\hspace{0.17em}}...,\text{\hspace{0.17em}}n-1$

where

• Y represents filtered signal
• n is the number of elements in signal
• Ji is a subset of signal centered about the ith element of signal
• the indexed elements outside the range of signal equal zero

The following equation describes Ji.

${J}_{i}=\left\{{X}_{i-rl},{X}_{i-rl+1},K,{X}_{i-1},{X}_{i},{X}_{i+1},K,{X}_{i+rr-1},{X}_{i+rr}\right\}$

where rl is the filter left rank, and rr is the filter right rank.

The following illustration shows the computation of Yi.

Where This Node Can Run:

Desktop OS: Windows

FPGA: Not supported