刘震昌个人经历

channel-optimized source coding
source Source coding EZW Channel property output Source decoding Noisy Channel
Proposed: Block-Based Multi-Channel Framework
D * (n) = ∑ (1 − p) i −1 p D(i − 1) + (1 − p ) n D(n)
Probability that the first error occurs at the i-th bit Given n bits, the expected value of distortion
研究方向
Wavelet-based signal processing
Estimation of fractional Brownian motion Robust compressed image transmission over IP/wireless network Object tracking using active contour model
Application: texture segmentation(2)
fBm mosaic
A Multi-Channel ChannelOptimized Scheme for EZW using Rate-Distortion Functions
Jen-Chang Liu, National Taiwan University Wen-Liang Hwang, IIS, Academia Sinica, Taiwan Wen-Jyi Hwang, Chung-Yuan Christian University Ming-Syan Chen, National Taiwan University
2α
+ K ns
−2
Application: de-nosing
original
original+ random noise
de-noised
Application: coastline detection
threshold
de-noising
Application: texture segmentation
Due to high correlation in the EZW encoded bitstream =>single bit error will propagate to the whole image
Hereafter are false decoded
EZW Bit stream
error
Solution Step 2: Bit Allocation
with Rate-Distortion Constraints
?
Problem: how to allocate bits to each block? Idea : using rate-distortion function of each block.
Estimation of 2-D Fractional Brownian Motion(fBm) using Wavelets
2-D fBm: examples
α=0.2
α=0.5
α=0.8
2-D Isotropic Fractional Brownian Motion
Non-stationary stochastic model for natural scenes and textures 1/f spectrum σ 2 P (w ) = 2α + 2 w
Bit Allocation with RateDistortion Constraints (cont.)
Optimal bit allocation using rate-distortion
constraints.
min
∑
K
i=1
D i (bi )

subject to
∑
K
i=1
bi ≤ R
where Di(bi) is the rate-distortion function for block i , and R is the total bit budget.
0 1
bit error rate(BER) = p
Add Noise Property into RateDistortion Function (cont.)
Statistical rate-distortion function for
some block
n i =1
Distortion with (i-1) correct bits
noisy channel property? Solution : taking noise parameters in the rate-distortion function. Case: memoryless Binary Symmetric
Channel (BSC)
0 1
1-p p p 1-p
Review of EZW coder
EZW(Embedded Zerotree Wavelet) State-of-the-art low bit rate still image coder proposed by Shapiro in 1993. Embedded : encodings of the same image at lower bit rate are embedded in the beginning protion of the bit stream for the target bit rate. Wavelet : discrete wavelet transform Zerotree : grouping of inter-band coefficients by zerotree symbol.
論文著作(2)
會議論文
1998 IEEE Symposium on Time-Frequency and Time-Scale Analysis, “Parameter estimation and denoising of 2-D noisy fractional Brownian motion using nonorthogonal wavelet” 1999 IEEE Int’l Conf. on Image Processing, “Robust blockbased EZW image compression with channel noise optimized rate-distortion functions” 2000 IEEE Int’l Conf. on Image Processing, “A multichannel channel-optimized scheme for EZW using rate-distortion functions” 2001 IEEE Int’l Conf. on Image Processing, “Waveletbased active contour model for object tracking”
劉震昌個人經歷
學歷
博士: 台灣大學電機工程所 1998~ 碩士: 交通大學資訊工程所 1994~1996 : 學士: 交通大學資訊工程系 1990~1994
工作經歷
中研院資訊所 研究助理(國防役) 1996/10 ~
指導教授
中研院資訊所 黃文良副研究員 台大電機系 陳銘憲教授
論文著作
期刊論文
1996 IEEE trans. on Consumer Electronic,”A new intensity stereo coding scheme for MPEG1 audio encoderLayer I and II”(指導教授: 交大資工 劉啟民教授) 2000 IEEE trans. on Image Processing, “Estimation of 2-D noisy fractional Brownian motion and its applications using wavelets” Submitted to IEEE trans. on Image Processing, “A blockbased channel-optimized source coding for EZW-like progressive codec using rate-distortion analysis”(與中 原大學電機系 黃文吉教授合作) Submitted to IEEE trans. on Circuits and Systems for Video Technology, “Active contour model using wavelet modulus for object segmentation and tracking in video sequences”(與陽明大學微免所 林奇宏教授合作)
α: scaling exponent(0<α<1), which is related to fractal dimension and surface roughness
Statistical self-similar property
Network traffic model is shown to exhibit self-similar property
Corrupted EZW
Burst noise
Our approach
Wavelet-based Active Contour Model(Snake) for Object Tracking