The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences. Vol. XXXVII. Part B7. Beijing 2008 
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obtained by low-pass filter with the pan-band, this study use the 
low-pass filter operator of 5*5 of ERDAS8.7. 
3.1.3 Brovery Change Fusion Method 
Brovery fusion formula as follows: 
B 
lowD high 
MB, 
Ills 
low,,, 
(3) 
3.1.5 IHS Transform Fusion Method 
At present, IHS transform model mainly contains spherical 
transform, cylinder transform, triangular transform and six 
pyramid transform. On the image fusion, the differences 
between the four models are not obvious, but sphere 
transform is the best in compare [9] . 
In this study use IHS transform method for the fusion 
experiment, and programming in Matlab to achieve the fusion 
algorithm. 
In the formula, d is the fusion image, n is bands numbers, 
J-J MB 
denominator denote the summation of the three ETM+ multi- 
spectral bands. 
3.1.4 The Product Transform Fusion Method 
The product fusion method is a simple algebra operation, multiply 
the pixel of the two images to obtain the fusion image. In this 
paper, take extraction with the product of the pixel to obtain the 
fusion image pixel value, the fusion algorithm formula as follows: 
ML^^XS^PN^ 
3.1.6 Principal Component Fusion Method 
The image after fusion contains the character of high spatial 
resolution image and high spectral resolution of the original 
image, reserve the high frequency of the original image. The 
individual part character of the aim of the fusion image is 
more clear, and the spectral information is more richer, and 
PCA transform conquer the localization of the HIS transform 
which can only at the same time do fusion with three bands, 
it can do fusion with more than two multi-spectral image. 
3.2 Fusion Image Evaluation Parameters 
The common used image fusion quality evaluation 
parameters are: the mean, standard deviation, average 
gradient, information entropy, and the correlation coefficient. 
In the formula, ML. jk is the fusion image pixel value, XS jjk is the 
pixel value of multi-spectral image, PN.. is the pixel value of 
panchromatic. 
4. EXPERIMENTS AND ANALYSIS 
Programming the various fusion algorithm with Erdas Model 
module and matlab, fused images are displayed: 5, 4 and 3 
bands in accordance with the R, G, B, fusion results are 
shown as follows(figurel-6): 
Figure4.ML fused image 543bands Figure5.PCA fused image 543bands Figure6. HIS fused image 543bands