The International Archives of the Photogramme try, Remote Sensing and Spatial Information Sciences. Vol. XXXVII. Part Bl. Beijing 2008 
means that the NIIRS values estimated through image analysis 
may indicate the true interpretability of the image. 
4. CONCLUSIONS AND FUTURE WORK 
So far, we described experiments carried out to compare the 
NIIRS values provided in the image metadata, the NIIRS values 
estimated by human operator and the NIIRS values estimated 
through image analysis. The NIIRS values provided in the 
metadata were larger than the values estimated by human 
operator. This could mean that the value in the metadata 
assumes ideal conditions and the exact cause of this difference 
is under current investigation. 
The NIIRS values estimated through image analysis were lower 
than the values estimated manually. However, they showed the 
same pattern as the NIIRS values estimated manually, 
indicating that the NIIRS values estimated though image 
analysis using the General Image Quality Equation can 
represent actual interpretability of the image. This also indicates 
that if we can provide edge points automatically we may 
achieve fully automatic estimation of NIIRS values. 
Precondition for this conclusion is that we need to find out the 
cause of deviation in the NIIRS values through image analysis 
and the values from human operators. This is under current 
investigation. 
The contribution of this study is that we proved the reliability of 
image analysis methods for calculating NIIRS values and 
showed the possibility of an automated technique of estimating 
NIIRS from images so that the value of NIIRS is systematically 
calculated at satellite ground stations. 
REFERENCES 
IRARS Committee, 1996. Civil NIIRS Reference Guide. 
http://www.fas.org/irp/imint/niirs_c/index.html (accessed 30 
April 2008) 
Leachtenauer, J. C., Malila, W., Irvine, J., and Colburn, L., 
1997. General Image-Quailty Equation: GIQE. Applied Optics, 
36(32):8322~8328 
Blonski, S., Ross, K., Pagnutti, M., and Stanley, T., 2006, 
Spatial Resolution Characterization for Aerial Digital Imagery. 
SSTI-2220-0071, NASA Technical Report Server 
http://ntrs.nasa.gov (accessed 30 April 2008) 
Ryan, R., Baldridge, B., Schowengerdt, R. A., Choi, T., Helider, 
D. L., and Blonski, S., 2003. IKONOS spatial resolution and 
image interpretability characterization. Remote Sensing of 
Environment, 88(01 ):37-52 
ACKNOWLEDGEMENTS 
The work in the paper is supported by research grant from 
“Kompsat-3 System Development Project” of Korea Aerospace 
Research Institute. 
Figure 4. Comparison of PNIIRS, TNIIRS and INIIRS