International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part B-YF. Istanbul 2004 
  
When telescope assembles of a sensor are not centralized to a 
ground point or if detector sets are not synchronized accurately, 
band to band misregistrationappears and if the image is not 
misregistration 
rectified properly, 
(figure 6). 
image to map occurs 
  
Figure 6. Image No.6 (MODIS) Image to map misregistration 
3. PRACTICAL STUDY RESULTS 
In a comparative study on some satellite images the following 
results were obtained: 
a) TERRA-MODIS images have very high geometricQuality 
except one systematic error called BOWTIE effect caused by 
multi detector scan line system that could be removed easily 
and accurately. Another error caused by multdetector scan line 
imaging system of MODIS is intense striping. MODIS bands 
systematically have a specific relative delay that causes a slight 
spatial misregistration of corresponding pixels. 
b) NOAA-AVHRR images are of high radiometric Quality 
especially thermal channels, but drop lines were observed 
frequently. 
c) IRS-PAN images despite their high resolution, have not 
appropriate geometric Quality because of misregistration of 
detector array. Also these images have intenseperiodic and 
random noise that should be removed and enhanced in seeral 
stages. 
d) IRS-LISSIII images have relatively better Radiometric 
Quality although band missing is reported sometimes. 
4. QI AND DEFECT ELIMINATION 
Once the defect or the problem is recognized, the elimination or 
improvement process can be perforned. But it should be noted 
that sometimes defect elimination could not be accomplished 
perfectly and also however in improvement process the desired 
element enhances but other elements may be destroyed. For 
example geometric correction imposes a radiometu blending 
because of resampling and also noise reduction blurs the image. 
So there should be an equilibrium point to balance the 
destructions (Watson 1993). 
106 
4.1 Radiometric Quality Improvement 
A quick reference for radiometricQuality improvement could 
be found in Table4. 
  
  
  
  
Quality Defect Manual Automatic 
Elimination Elimination 
Striping Equalization of Removing the 
mean and variance | related frequency 
of adjacent lines Zone in spectrum 
Drop Line Replacement of an | Replacement of 
adjacent line mean of adjacent 
lines 
Noise Averaging , Median and 
Spatial filters 
adaptive filters 
  
  
Band Missing 
  
  
Replacing a 
combination of the 
other bands 
  
  
Table 4. Radiometric Quality defects and improvement 
methods 
Regarding the cause of striping defect, theelimination must be 
performed in order to equalize the appearance of the adjacent 
lines (figure 7) (Richards & Jia1999). 
#4 
A oe 
  
Figure 7. Image No.l (MODIS) Destriped 
Drop lines are simply loss of data and merely could be 
eliminated by replacing the other lines or a composition of them 
(figure 8). 
  
Figure 8. Image No2 (AVHRR) after drop line removal