International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part B-YF. Istanbul 2004 
The combination entropy (C.E.) represents the property of 
combination between images. The larger the combination 
entropy of an image, the richer the information contained in the 
image. In Table 1, the combination entropy of the curvelet- 
based image fusion is greater than those of other methods. Thus, 
the curvelet-based image fusion method is better than the 
wavelet and IHS methods in terms of combination entropy. 
The mean gradient (M.G.) reflects the contrast between the 
details variation of pattern on the image and the clarity of the 
image. And the correlation coefficient (C.C.) between the 
original and fused image shows the similarity in small size 
structures between the original and synthetic images. In Table 1, 
the mean gradient and the correlation coefficient of the 
curvelet-based image fusion method are grater than those of the 
wavelet-based image fusion method. As previously stated, if the 
object of image fusion is to construct synthetic images which 
are closer to the reality they represent, then the curvelet-based 
image fusion method meet this objective very well. This is one 
of the main advantages of using the curvelet transform for 
image fusion. 
Based on the experimental results obtained from this study, the 
curvlet-based image fusion method is very efficient for fusing 
IKONOS images This new method has reached an optimum 
fusion result. 
6. CONCLUSIONS 
We have presented a newly developed method based on the 
curvelet transform for fusing IKONOS images. In this paper, an 
experimental study was conducted by applying the proposed 
method, and also other image fusion methods, for fusing 
IKONOS images. A comparison of the fused image from the 
wavelet and IHS method was made. 
Based on the experimental results respecting the four indicators 
— the combination entropy, the mean gradient, and the 
correlation coefficient, the proposed method provides a good 
result, both visually and quantitatively, for remote sensing 
fusion. 
ACKNOWLEDGEMENT 
The first author much thanks Korea Aerospace Research 
Institute for providing the raw IKONOS images for this 
research. 
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