RESEARCH ON FALSE COLOR IMAGE COMPOSITE AND ENHANCEMENT 
METHODS BASED ON RATIO IMAGES 
Liang Jun a,b ’ *, Chen Songwei c , Li Duanyou 3b , Wang Bin 3 , Liu Shuo d , Zhou Liming 3 
a .Yangtze River Scientific Research Inst,Wuhan 430010, China - keyindex@163.com 
b Research Center on Water Engineering Safety & Disaster Prevention of MWR,Wuhan 430010,China 
- keyindex@163.com 
c Taizhou Radio&Television University, Taizhou 318000, China - chensw@tztvu.zj.cn 
d The Institute of Remote Sensing Applications, Chinese Academy of Sciences (1RSA/CAS), Beijing 100101, China 
Commission WG VII/6 
KEYWORDS: Remote Sensing image; Ratio Image; False Color Image Composite Method; Texture Analysis; Sliding Window 
Method ; the Optimal Scale ;OIF method; 
ABSTRACT: 
By referencing rock spectrum reflection curves, the effective bands of remote sensing images are selected which are treated with ratio 
processing in this paper. False color composition is proceeded by two ratio images and a single band. After this, the single band 
restored the terrain detail information which is lost in the other two ratio images. Then sliding window method is used to analysis the 
distribution of texture. A series of characteristic matrix are generating by computing the characteristic value of different scales of the 
windows which including the texture statistical information of remote sensing images. In this paper OIF(The Optimum Index Factor) 
method is adopted to proceed the objective evaluation which can find the optimal scale of sliding windows and to proceed the false 
color composite with ratio characteristic matrixes. The size of optimal sliding windows is found by multiple tests on contrasting 
image and referencing ground resolution of remote sensing images. 
1. INTRODUCTION 
By researching different bands characteristics of RS images, 
ratio processing is proceeded by selecting several bands in this 
paper. The method of false color composite is proceeded by 
ratio images in order to find the region distribution information 
with rich with mineral content which will be benefit for 
prospecting work.. Then the OIF(The Optimum Index Factor) 
value is used to estimate the quality of the images we have got. 
Finally the optimal sliding window is discussed by using 
sliding window method by the end of process. 
2. RATIO ENHANCEMENT METHOD 
Ratio enhancement is an often used image enhancement 
method, which make pixel brightness of two different bands 
divided with the propose of generating new ratio image. 
Though making the relevant bands divided considering the 
reflection peaks and the absorption peaks , the content 
proportion of specific information is improved and other 
unnecessary information is depressed. And this method can 
decrease the intensity roughness caused by the effect of 
reflectivity and terrain slope. 
For example, watching the iron ore mineral spectrum curve, 
we can find that there is a strong reflection peak in band 5 
curve ,and there are two strong absorption peaks in the same 
wavelength in band 1 and band 4. In order to increase the 
information of iron element, two different ration combination 
can be selected. One is that band one divided by band five, the 
other is that band four divided by band five. And the 
following image is a ratio image which can be obtained by 
dividing with band one and band five. 
Figure. 1 Ratio image of band five and band one 
3. FALSE COLOR IMAGE COMPOSITE OF RS 
IMAGES 
Human eyes can distinguish teens gray scales for grey image. 
However for color image ,the capability of human eyes is 
stronger than that of grey one. People can distinguish more than 
13000 different colors by machine[l,2]. So the method of False 
Color Image Composite is most commonly used for visual 
interpretation. Three grey images can combined into one color 
image which can show us more different objects features. 
* Correspondence to: Liang Jun(E-mail: keyindex@163.com) or Chen Songwei (E-mail: chensw@tztvu.zj.cn) 
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