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Improvement of Zernike Moment Descriptors
on Affine Transformed Shapes
Adviser: 李育強
Speaker: 楊智雁
Date:2010/01/18
Signal Processing and Its Applications, 2007. ISSPA 2007. 9th International
Symposium on
南台科技大學
資訊工程系
Outline
2
1
Introduction
2
Proposed Algorithm
3
Experimental Results
4
Conclusion
1.Introduction
 Skew and stretch distortions are common among
shapes obtained from natural objects
 Zhang and Lu proposed a method which involves
rotation and scale normalization
 We propose a new method for extracting Zernike
moments addressing this issue
3
2. Proposed Algorithm
 Three second order geometric moments for a
region
  
(   )


2
f (  , y)
 y   (    )( y  y) f ( x, y)

y
 yy   ( y  y) 2 f (  , y )
y
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2. Proposed Algorithm (c.)
R  {(  , y) | d   2exy  f y  1}
2
5
2
2
2
2. Proposed Algorithm (c.)
1
x 
a

 '

y 
0

'
 1
 x' '   d max
 y ' '  
   0


6

0   cos 
1 
   sin 
b

0 
 x'
 
1   y '
d man 

sin    x  x 


cos  
 y  y
3. Experimental Results
1.Rotation and scale as Linear invariance properties
2.Stretching and skew as Non-linear invariance
properties
7
3. Experimental Results (c.)
We evaluate linear invariance properties, by
comparing the performance of the proposed
method to Bin’s reported work
r 
8
Z  Z
Z
'
3. Experimental Results (c.)
9
3. Experimental Results (c.)
10
3. Experimental Results (c.)
11
4. Conclusion
 We proposed a new method to improve the
stretch and skew invariance properties of
Zernike moments
 Retains the rotation and scale invariance
properties as well
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南台科技大學
資訊工程系