Security. Computer Center, CS, NCTU 2 FreeBSD Security Advisories – (1) .
Final Project - NCTU
Transcript of Final Project - NCTU
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Final Project
June 28th, 2013
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2Agenda
Base Color and Index Map RepresentationSliding Window Lempel‐Ziv CodingMandateTest ConditionsSubmission Requirements
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3Base Color and Index Map, BCIM
Convert a block into base colors and index mapIndex specifies the base color a pixel is mapped to
[Block Samples]
Intensity Value
0 1 2 3 4 5 6 7 8 9 10
Pro
babi
lity
p(x)
x
Index
0
1
2 34
5
6
7
89
Base Color
[Index Map]
0000
0000
44 4
4
444 4
Analysis Conversion
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4Entropy Estimation
Number of Base Colors (K)
Index Map and Base Colors of ith Block
Entropy
255
2 210
1log 2 log 1 1iB
xH X p x p x x
p x
1i
KBCIM B
iS B
NH X H K H XN N
2 21
1log 2 log 1d
H K p k p k kp k
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5Sliding Window Lempel‐Ziv, LZ77 (1/2)
Encode a string by finding the longest match within a search buffer of past samplesRepresent the string by the location of the match within the buffer and the length of the match.
x x a b r a x a a b r a t r Search Buffer Matched String
x x a b r a x a a b r a t r Search Buffer (e.g. Shifted by 4)
Shift theSearch Buffer
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6Sliding Window Lempel‐Ziv, LZ77 (2/2)
Need a flag, F, for specifying match and mismatchMatch– D: representing the location of a match – L: representing the length of a match.– E.g. {a, b, r, a}
Mismatch– C: representing an uncompressed character– E.g. {t}
x x a b r a x a a b r a t r
x x a b r a x a a b r a t r
F=1, L=4, D=6-L=2
F=0, C=t
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7Entropy Estimation
Flag (F)
Location (D)
Length (L)
Character (C)
Entropy
| 1 | 1 | 0F D L CLZ
S
N H F N H D F N H L F N H C FH X
N
21log
f
H F p fp f
2 21
1| 1 | 1 log | 1 2 log 1 1| 1d
H D F p d F p d F dp d F
2 21
1| 1 | 1 log | 1 2 log 1| 1
H L F p F p Fp F
2 21
1| 0 | 0 log | 0 2 log 1| 0c
H C F p c F p c F cp c F
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82D‐to‐1D Conversion for LZ77
Convert past blocks and current block into a 1‐D arrayProcess a picture on a block‐by‐block basis
x x a b r a x a a b r a t r
CurrentBlock
Initial Search Buffer Current Block Samples
2D-to-1DConversion
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9Mandate: LZ77 vs. BCIM
Compare HBCIM(X) with HLZ(X) under various settings of block sizes & buffer lengths
(Entropy) LZ77 BCIM4KB 16KB 64KB8x8
16x1632x3264x64
(LZ77)p(F=1) E[D|F=1] E[L|F=1]
4KB 16KB 64KB 4KB 16KB 64KB 4KB 16KB 64KB8x8
16x1632x3264x64
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10Common Test Condition
64
H
W
W%64
H%64
N
N13X
CurrentBlock
2X‐1
Only Y samples in the center areaare counted in for comparison
A block within search buffer“X” is derived as follows:e.g. Given a 8 KB buffer and N=16 => X=64KB/162Byte=256
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11Common Test Sequences (1/2)
sc_ppt_doc_xlssc_map SlideEditing SlideShow
VennueVue sc_cg_twist_tunnel cad_waveform sc_pcb_layout
KimonoChinaSpeed EBURainFruits
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12Common Test Sequences (2/2)Content Type Resolution Sequence
Name Bitdepth FrameCount *
Color Format
ScreenContent
(w/o Noise)
1920x1080
VennueVue 8 90
YUV 4:4:4
cad_waveform 8 60pcb_layout 8 60ppt_doc_xls 8 60
1280x720
vc_doc_sharing 8 90web_browsing 8 90cg_twist_tunnel 8 90wordEditing 8 180programing 8 180
map 8 180ScreenContent
(w/ Noise)
1280x720 SlideEditing 8 90
YUV 4:2:0SlideShow 8 60
1024x768 ChinaSpeed 8 90
NatureScene 1920x1080
Kimono 8 72ParkScene 8 72
EBURainFruits 8 150 YUV 4:4:4
Link: http://mapl.nctu.edu.tw/course/VC_2013/files/final_proj/seq.rar(* Password required)
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13Submission Requirements
Requirements– Detailed discussion on the reported results is a MUST– Step‐by‐step guidance to compile/run your software
Submission Format– A zip archive contains (1) a report, (2) source code(s), (3) binary executable(s)
– File name of the archive should be StudentID‐Name.zip
General Information– Due date: July 12, 2013– Overdue submission penalty: ‐30%
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14Reference
C. Lan, and et. al., "Compress Compound Images in H.264/MPGE‐4 AVC by Exploiting Spatial Correlation," IEEE Transactions on Image Processing, vol.19, no.4, pp.946‐957, April 2010
T. Lin, and et. al., "Mixed Chroma Sampling‐Rate High Efficiency Video Coding for Full‐Chroma Screen Content," IEEE Transactions on Circuits and Systems for Video Technology, vol.23, no.1, pp.173‐185, Jan. 2013
T. M. Cover and J. A. Thomas, "Elements of Information Theory," 2nd Ed., Wiley, 2006. (Chap 13.4)
Link: http://mapl.nctu.edu.tw/course/VC_2013/files/final_proj/ref.zip
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Fun~~Have