英文文献及翻译：级联迭代傅里叶变换算法在光学安全中的应用.doc.doc
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河南科技大学本科毕业设计（论文）
A
cascaded
iterative
F
ourier
transform algorithm
for optical
security
applications
A b s t r a c t:A c a s c a de d it er a t i v e Fo ur i e r t r a ns fo r m ( CI FT ) a l g o r i t h m i s p r es e n te d fo r o p t i c a l
s e c u r i t y a p p l i c a t i o n s . T w o p h a s e - m a s k s a r e d e s i g n e d a n d l o c a t e d i n t h e i n p u t a n d t h e
F o u r i e r d o m a i n s o f a 4 - f c o r r e l a t o r r e s p e c t i v e l y , i n o r d e r t o i m p l e m e n t t h e o p t i c a l
e n c r y p t i o n o r a u t h e n t i c i t y v e r i f i c a t i o n . C o m p a r e d w i t h p r e v i o u s m e t h o d s , t h e p r o p o s e d
a l g o r i t h m e m p l o y s a n i m p r o v e d s e a r c h i n g s t r a t e g y : m o d i f y i n g t h e p h a s e - d i s t r i b u t i o n s o f
both masks synchronously as well as enlarging the searching space. Computer simulations
show that the algorithm results in much faster convergence and better image quality for the
r e c o v e r e d i m a g e . E a c h o f t h e s e m a s k s i s a s s i g n e d t o d i f f e r e n t p e r s o n . T h e r e f o r e , t h e
de c ryp t ed i mag e ca n be ob ta i ne d o n ly wh en a ll t he s e ma s k s a re u n de r au t h ori z at i on . T hi s
key-assignment strategy may reduce the risk of being intruded.
Ke y wo r d s : O p t i c a l s e c u r i t y – o p t i c a l e n c r y p t i o n – c a s c a d e d i t e r a t i v e Fo u r i e r
transform algorithm
1. Introduction
O p t i c a l t e c h n i q u e s h a v e s h o w n g r e a t p o t e n t i a l i n t h e f i e l d o f i n f o r m a t i o n s e c u r i t y
a p p l i c a t i o n s . R e c e n t l y R é f r é g i e r a n d J a v i d i p r o p o s e d a n o v e l d o u b l e - r a n d o m - p h a s e
e n c o d i n g t e c h n i q u e , w h i c h e n c o d e s a p r i m a r y i m a g e i n t o a s t a t i o n a r y w h i t e n o i s e . T h i s
technique was also used t o en c r y p t i n f o r m a t i o n i n t h e f r a c t i on a l F o u r i e r d o m ain a n d t o
store encrypted information holographically. Phase encoding techniques were also proposed
for optical authenticity verification.
Wa n g e t a l a n d L i e t a l p r o p o s e d a n o t h e r m e t h o d f o r o p t i c a l e n c r y p t i o n a n d a u t h e n t i c i t y
v e r i f i c a t i o n . U n l i k e t h e t e c h n i q u e s m e n t i o n e d a b o v e , t h i s m e t h o d e n c r y p t s i n f o r m a t i o n
completely into a phase mask, which is located in either the input or the Fourier domain of a
4 - f c o r r e l a t o r . F o r i n s t a n c e , g i v e n t h e p r e d e f i n i t i o n s o f a s i g n i f i c a n t i m a g e f ( x , y ) a s t h e
d e s i r e d o u t p u t a n d a p h a s e - d i s t r i b u t i o n e x p { j b ( u , v ) } i n t h e F o u r i e r d o m a i n , i t ’ s e a s y t o
optimize the other phase function exp{jp(x, y)} with a modified projection onto constraint sets
(POCS) algorithm [10]. Therefore the image f(x, y) is encoded successfully into exp{jp(x, y)}
with the aid of exp{jb(u, v)}. In other words, the fixed phase exp{jb(u, v)} serves as the lock
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