The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences. Vol. XXXVII. Part B7. Beijing 2008 
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2(c) SPOT Pan image 
Figure 2.The co-registered images 
information,simultaneously, preserves spectral content of the 
MS image. The proposed approach is effective for image 
interpret and classification. Its effectiveness for urban object 
extraction will be presented in the other paper. 
Entropy 
Average 
gradient 
Correlation 
coefficient 
5.40 
9.33 
1.0 
TM images(band 
5.32 
5.90 
1.0 
3,4,5) 
6.25 
13.92 
1.0 
The fused 
5.82 
10.02 
0.89 
5.57 
7.61 
0.88 
images 
By the proposed 
method 
6.53 
14.55 
0.90 
Table 1. Evaluation of the fused image 
Figure 3.The fused images 
3.1 Visual examination 
Compared with from figure 2(b) and figure 3, urban and built- 
up areas, as well as roads are clearly enhanced and almost 
perfect preservation of spectral signatures is visible in the fused 
images. Visual examination suggests that the fused images are 
higher in spatial resolution than that of the Landsat TM images, 
and have better visual effect. Due to limitations of human vision, 
comparison and appreciation by visual methods does not reveal 
the exact potentials of the fusion methods. Hence, a comparison 
of image statistics is attempted to evaluate the results of fusion. 
3.2 Quantitative analysis 
In addition to visual analysis, we conduct a quantitative 
analysis. We base our analysis of the experimental results on 
entropy, average gradient of the fused images and correlation 
coefficient (Table 1) between the fused images and the Landsat 
TM images. 
In Table 1, we show that the entropy and the average gradient 
are bigger than the corresponding values of the TM images. The 
correlation coefficient between the fused images and the 
Landsat TM images is very high. From these results, we can say 
that the proposed fusion method provides more detailed spatial 
4. CONCLUSION 
A new image fusion method of SAR, Panchromatic (Pan) and 
multispectral (MS) data is proposed. The SAR texture 
extraction and high pass details of Pan image modulated with 
the SAR texture are reasonable.The proposed method can 
improve spatial resolution and simultaneously preserve spectral 
content of the MS image ,and is effective for image interpret 
and classification. For future work, the authors would be 
looking at evolving to a more autonomous fusion system. 
ACKNOWLEGEMENT 
The authors would like to express their sincere gratitude to the 
anonymous referees for pointing out several typos and for some 
very helpful comments. 
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