Gamma LAT: Reference Manual

enh_lee

ANSI-C program: enh_lee.c

NAME
enh_lee - Enhanced Lee filter for power files of type float (Lopes et. al. 1990).

SYNOPSIS
enh_lee <input_data> <output_data> <width> <nlooks> <damp> <bx> [by]

<input_data>	input data (file of type float)
<output_data>	output data (file of type float)
<width>	number of samples/row
<nlooks>	number of looks
<damp>	damping coefficient of the filter
<bx>	filter size in x direction (number of cols)
[by]	filter size in y direction (number of rows)(default=bx)

EXAMPLE
enh_lee 1352_1610.pwr1 1352_1610.pwr1_enh_lee 2500 4 11 11

INSTALLATION
Source code enh_lee.c in ./src. For compilation adjust and use Makefile: Executable version enh_lee in ../bin

AVAILABILITY
Uses type definition file typedef_ISP.h.

DESCRIPTION
The enh_lee filter performs filtering based on the Enhanced Lee filter proposed by Lopes et. al., 1990. The Enhanced Lee filtering is primarily used to remove speckle while preserving edges. The Lee filter was first proposed by Lee (1980). Lopes (1990) modified the Lee filter by setting up two thresholds. Input parameters are the filter box size, the number of looks and the damping coefficient. Different filter sizes will greatly affect the quality of the processed image. If the box size is to small, the noise filtering is not effective. If the filter is too large, fine structures will be lost. The nlooks parameter refers to the number of looks of the radar image. It is used to compute the noise variance.

OPTIONS
Number of looks of input image, damping coefficient and userdefined filter window size (odd numbers).

SEE ALSO
typedef_ISP.h, average_filter lee frost .

DIAGNOSTICS
All messages are generally self-explanatory.

NOTES
None.