International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part B4. Istanbul 2004 
limitations (Mulder, 1986). Enhancement is used to improve 
the image's interpretability. Saturation enhancement, which 
is a part of the colour coding, is implemented by using the 
linear 3 x 3 matrix transformation on the multispectral data: 
R' : R 
G'|=|M'A M| \G 
p B 
ml M] R 
m2|-— |. M2 pl u G 
7 7 
1 I B 
The main purpose of M mapping is to transform the RGB 
domain into the intensity normalized R^ G^ B' where we can 
specify change in colour balance, change in hue and change 
in saturation, independent of intensity. ml and m2 are 
orthogonal axes in the two-dimensional colour triangle R^ G' 
B? derived from the colour space (colour cube). “The colour 
space is a linear space in which the mixture of two additive 
colours is equivalent to a colour vector which is a linear 
interpolation of the mixing colour vectors" (Mulder, 1986) 
(see Figure 3). 
  
  
  
G 
i 
€ i 
i 
i 
Ber 
8 
  
  
Figure 3. The colour cube and the colour triangle 
A is a matrix which performs an affine transformation of the 
data triangle onto the corners of the colour triangle by 
bringing the vegetation to green, the soil to red and the water 
to blue (Figure 4). 
  
   
w=water 
$= soil 
v=vagatation 
    
  
  
  
  
Figure 4. Affine transformation with A matrix 
M'! is the inverse of M which brings back the data from the 
MI, M2 I domain into the RGB coordinate system (the colour 
cube). Before the execution of the matrix multiplication, 
however, parameters for colour enhancement were derived 
750 
from the scatter diagram on ml, m2. A two-dimensional 
scatter diagram of ml and m2 was made for this purpose. The 
colour triangle was drawn onto the scatter diagram (Figure 
5). In this study, the A matrix implements only a saturation 
enhancement (stretching and shifting on the m1, m2 axes). 
  
Mae: and dE | 
  
  
  
  
  
st ve que sq di 
es 1 * mg "T a T T a "t € 
  
  
  
Figure 5. A two dimensional scatter diagram of m1 and m2 
The saturation enhancement is implemented by using the 
resulting matrix as a multiplication factor to the RGB 
coordinates of the original image to obtain the new R'G'B' 
coordinates (as new feature files) of the colour enhanced 
image. Figure 6 shows the scatter diagram after saturation 
enhancement. 
  
  
  
  
  
  
As 
Ware epe pq pterea tique AT ap et 
  
  
Figure 6. Scatter diagram after saturation enhancement 
6. COMBINATION OF PANCHROMATIC AND 
MULTISPECTRAL BANDS 
Many applications of remote sensing image data require two 
or more images of the same area to be represented together 
for various purposes (eg, change detection). Having the high 
resolution panchromatic 10 m ground resolution and the 
multispectral 20 m, the basic idea was to merge them to use 
the double data set to get a better image with more details. 
Different experiments were carried out to illustrate this 
combination: 
(1) enhanced panchromatic plus the haze-corrected 
multispectral with saturation enhancement of 
colours; 
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