The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences. Vol. XXXVII. Part B7. Beijing 2008 
The correlation coefficient reflects the redundancy degree of 
images. According the table 1,we know the original image 
contains a plenty of redundant information and the correlation 
coefficient of fused image based on three-band biorthogonal 
wavelet is less than that of original image and other fused image 
except of fused image based on PCA, which indicates that this 
method has less redundant information . 
The mean gradient reflects the contrast between the details 
variation of pattern on the image and the clarity of the image. 
Of all images including original TM image ,the fused image 
based on three-band biorthogonal wavelet transform has the 
most mean gradient. 
According to previous statistics and analysis, we can draw a 
conclusion that the fusion method based on three-band 
biorthogonal wavelet is efficient for merging low resolution 
multi-spectral TM image and high resolution Spot panchromatic 
image.lt has many advantages in comparison with other 
methods when the ratio of spatial resolution of original image is 
not two.Certainly other fusion methods have advantage in some 
ways. 
Method 
MG 
SD 
CC 
CE 
34.07 
46.72 
0.296 
35.73 
52.38 
0.389 
PCA 
26.95 
53.30 
-0.25 
7.668 
31.77 
53.14 
0.647 
32.12 
46.45 
0.774 
IHS 
27.52 
52.83 
0.617 
7.661 
33.39 
52.81 
0.776 
Brovey 
34.31 
27.68 
46.07 
0.661 
7.683 
52.99 
0.463 
3-band 
39.82 
56.33 
0.578 
Biorthogonal 
44.63 
52.93 
0.523 
7.786 
Wavelet 
33.95 
58.83 
0.00718 
Original 
35.89 
52.89 
0.587 
7.70 
Image 
36.81 
49.40 
0.533 
(TM) 
29.99 
55.14 
0.03 
Table 1 the comparison of fused image of different methods 
5. CONCLUSIONS 
In this paper, a new fusion method based on three-band 
biorthogonal wavelet was presented to merge the multi-spectral 
TM and high resolution Spot panchromatic image. Several 
parameter including mean gradient, standard deviation, 
correlation coefficient and combination entropy were adopted 
to appraise the fused products. At last the result of experiment 
proves that the fusion method based on three-band biorthogonal 
wavelet is more efficient to fuse the TM 30m-resolution image 
and lOm-resolution Spot panchomatic image than other fusion 
methods. The reason is that biorthogonal wavelet is symmetric 
and three-band wavelet can produce the low frequency image 
which has the same resolution with low-resolution image.Thus 
the spectral information can be reseaved to the greatest extent 
and the distoration of spectral characters can be resolved. 
Further we can draw a conclusion that n-band biorthogonal 
wavelet has some advantages when the ratio of spatial 
resolution is n. So the multi-band biorthogonal wavelet can play 
a impotant role in image fusion. 
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