The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences. Vol. XXXVII. Part Bl. Beijing 2008 
parameters k and r to apply insitu operation on cA\ cH, cV 
and cD. 
If cA 7 (i, j)<k, 
then cH(i, j)=k, cV(i, j)=k, cD(i, j)=k; 
If (cH, cV, cD)(i, j)>r*var(cH, cV, cD), 
then (cH, cV, cD)(i, j)=r*var(cH, cV, cD); 
If (cH, cV, cD)(i, j)<-r*var(cH, cV, cD), 
then (cH, cV, cD)(i, j)=-r*var(cH, cV, cD). 
7) Apply the inverse discrete wavelet transform of the 
wavelet coefficient achieved in step 6. 
8) Carry out exponential transform of the values 
g 7 (x, y) obtained in step 7 to get the denoised image r(x, y). 
3. EXPERIMENTAL RESULTS 
3.1 Data Description 
Two SAR images covering Hulu Island area located in Liaoning 
province in China are used in our experiments. Also, two 
SPOT5 images of the same latitude and longitude are provided 
to do a comparison. More detailed information about these two 
SAR images and optical images can be seen in Table 1. 
Satellite 
Radarsat2 
Time of first data 
Jan, 15th, 2007 
Latitude at Image center (degree) 
40.7911434 
Longitude at image center (degree) 
120.5331714 
Incidence Angle (degree) 
44.716 
Number of azimuth looks 
1.0000000 
Number of range looks 
1.0000000 
Line spacing (m) 
6.2500000 
Pixel spacing (m) 
6.2500000 
Satellite 
SPOT5 
Time 
Sep, 17th, 2006 
Latitude at Image center (degree) 
40.840054 
Longitude at image center (degree) 
120.481283 
Incidence Angle (degree) 
13.885192 
Resolution (m) 
10.000000 
Instrument 
HRG 
Table 1. Specific information about experimental SAR and 
optical images 
3.2 Experiment I 
Several filters are employed on the SAR image, including: 
median, Lee, Lee-Sigma, Frost, Gamma-MAP, Wiener, wavelet 
threshold and ISPW method. Table2 lists all filter parameters 
used in the paper. These selected parameters do not imply the 
filters having been turned to the optimal. Instead the selection 
enables all filters to reduce speckle to an approximately similar 
level, so that analysis and comparisons can be fairly performed 
(Y. Dong, A.K. Milne and B. C. Froster, 2001). 
Filters 
Parameters 
Median 
Window size: 3*3 
Lee 
Window size: 3*3, 
Coefficient of Variation: 0.2 
Lee-Sigma 
Window size: 3*3, 
Coefficient of Variation: 0.2 
Frost 
Window size: 3*3, 
Coefficient of Variation: 0.2 
Gamma-MAP 
Window size: 3*3, 
Coefficient of Variation: 0.2 
Wiener 
Window size: 3*3 
Wavelet 
Threshold type: hard 
threshold 
Threshold method: Section (Anurat Ingun, 
1996) 
Table2. Filter parameters used in the paper 
Original SAR image and its corresponding SPOT5 image are 
shown in Figure2, denoised images of different filters are 
shown in Figure3. 
(a) (b) 
Figure2. Original SAR image (a) and corresponding SPOT5 
image (b) 
(e) (f) 
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