differences equal to -33 and +30 respectively with an R.M.S. of 
+/- 9.8 pixel grey-scale intensity values. 
  
(b) 
Figure 3. (a) A JPEG version (section only) of Peter for a 
compression ratio of 7:1 and (b) the same image reconstructed 
using the contour nodes for a contour increment equal to 5. 
The proposed compression process was further tested using the 
image of the /ake (400?) and the aerial view (400?) shown in 
Figure 4 and Figure 5 respectively. 
The maximum and minimum differences of pixel intensity 
values resulting from subtracting the JPEG version of lake jpeg 
from the original /ake.tif were respectively -39 and +51 grey- 
scale values with an R.M.S. equal to +/-38. By contrast, the 
contour approach produced maximum and minimum differences 
equal to -35 and +37 respectively with an R.M.S. of +/- 10.3 
pixel grey-scale intensity values. 
On the other hand, the maximum and minimum differences of 
pixel intensity values resulting from subtracting the JPEG 
version of aerial.jpeg view from the original aerial view.tif were 
respectively -35 and +47 grey-scale values with an RMS. 
equal to +/-35. By contrast, the contour approach produced 
maximum and minimum differences equal to -31 and +42 
respectively with an R.M.S. of +/- 7.8 pixel grey-scale intensity 
values. 
International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Volume XXXIX-B3, 2012 
XXII ISPRS Congress, 25 August — 01 September 2012, Melbourne, Australia 
  
Figure 5. The original image of /ake.tif (400?). 
  
Figure 5. The original image of aerial view.tif (400?). 
  
  
  
  
  
  
  
  
  
Contour | Accuracy | Memory Maximum | Minimum 
increments | R.M.S. required difference | difference 
2 3.7 0.172 Mb 6 8 
4 7.3 0.076 Mb 23 29 
6 10.6 0.064 Mb 35 34 
8 20.5 0.043 Mb 39 46 | 
  
  
  
Table 2. Accuracy and memory requirements needed to 
reconstruct the original image of /ake using contour increments 
between 2 and 8 grey-scale intensity values 
  
  
  
  
  
  
  
  
  
  
Contour | Accuracy | Memory | Maximum | Minimum 
increments | R.M.S. required difference | difference 
2 3.1 0.151 Mb 7 8 
4 6.8 0.062 Mb 21 31 
6 8.8 0.059 Mb 37 33 
8 18.4 0.041 Mb 39 44 
  
Table 3. Accuracy and memory requirements needed to 
reconstruct the original image of aerial view using contour 
increments between 2 and 8 grey-scale intensity values. 
  
    
    
   
  
  
    
    
     
    
        
    
    
    
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