Full text: XVIIIth Congress (Part B3)

  
Image Size Reduction 
  
Ex. lan | 786432 0 
Ex9% 84365 702067 
Ex11% 71090 715342 
Ex12% 65592 720840 
Ex13% 59345 727087 
Ex14% 55284 731148 
  
  
  
  
  
  
  
  
  
  
Table 4. Amount of Reduction in Storage for 
Experiement Ex (in bytes) 
5. CONCLUSION 
The problem of compressing images that are 
used for mapping using JPEG is of a 
compromising nature, since more compression 
saves a significant amount of space and 
facilitates image processing but causes 
appreciable loss of information. For some 
applications of digital mapping, compression 
might be very useful even if some information 
is lost. In this experiment, compressing the 
image up to 12%, is possible with little effects 
on the visual appearance and with appreciable 
changes in the pixels number of some classes. 
In this particular experiement, for a three-band 
TM image, more than 700 kb of storage could 
be saved in the compression process. If high 
accuracy is not necessary for identifying image 
features, the classification parameters can be 
adjusted to accommodate the minor changes in 
the pixels values. It is also noticed that the 
effect of JEPG is a scene-dependent matter. It 
seems that scenes of few heterogeneous classes 
may be more amenable to high compression rate 
than scenes with many homogeneous classes. 
ACKNOWLEDGEMENT 
The author would like to thank King Abdul Aziz 
City for Science and Technology (KACST) for 
provideing the TM data for this study. 
28 
International Archives of Photogrammetry and Remote Sensing. Vol. XXXI, Part B3. Vienna 1996 
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Jensen J., 1986. Introductory Digial Image 
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