# Multi Direction Lee Filter

Copyrights (c) 2003 by Andre Ringeler
This Multi Direction Lee Filter is a enhanced Lee Filter
It looks into 16 directions for the direction with the minium variance
and applied a Lee Filter on this direction.
Uses this filter for remove speckle noise in SAR images or DTMs.
On DTMs this filter will preserves the slope and narrow valleys.
For details on the Lee Filter, see the article by Jong-Sen Lee:
"Digital Image Enhancement and Noise Filtering by Use of Local Statistics",
IEEE Transactions on Pattern Analysis and Machine Intelligence,
Volume PAMI-2, Number 2, pages 165-168, March 1980.

## Parameters

Grid system
Grid system
  Grid system
Grid
Input Grid
Filtered Grid
Output Grid
Minimum Standard Deviation
Output Grid
Direction of Minimum Standard Deviation
Output Grid
Estimated Noise (absolute)
Floating point
  Estimated noise in units of input data
Estimated Noise (relative)
Floating point
  Estimated noise relative to mean standard deviation
Weighted
Boolean
Method
Choice
  Available choices: noise variance given as absolute value, noise variance given relative to mean standard deviation, original calculation (Ringeler)