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A practical Projection-Based Postprocessing of Block-Coded Images with Fast Convergence Rate. Yeonsik Jeong, Inkyeom Kim, and Hyunchul Kang. Blocking effect (1/2). Blocking effect is the problem of Block-Coded Image. Blocking effect (2/2). 5. 15. 3. 8. POCS(projection onto convex set). - PowerPoint PPT Presentation
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A practical Projection-Based Postprocessing of Block-Coded Images with
Fast Convergence RateYeonsik Jeong, Inkyeom Kim, and Hyunch
ul Kang
Blocking effect (1/2)
• Blocking effect is the problem of Block-Coded Image
Blocking effect (2/2)
POCS(projection onto convex set)
• reduction blocking effect
• SCS (smoothness constraint set)and QCS (quantization constraint set)
10 155
3 8
QCS(1/3)
Decoded image DCT coefficient
-416 -33 -60 32 48 0 0 0
12 -24 -56 0 0 0 0 0
-42 13 80 -24 -40 0 0 0
-56 17 44 -29 0 0 0 0
18 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0
16 11 10 16 24 40 51 61
12 12 14 19 26 58 60 55
14 13 16 24 40 57 69 56
14 17 22 29 51 87 80 62
18 22 37 56 68 109 103 77
24 35 55 64 81 104 113 92
49 64 78 87 103 121 120 101
72 92 95 98 112 100 103 99 Quantization table
QCS11 = [-416-16/2,-416+16/2] = [-424,-408]
QCS(2/3)
QCS11 = [-416-16/2,-416+16/2] = [-424,-408]
d11 = -425 PQCS(d11) = -424
d11 = -400 PQCS(d11) = -408
d11 = -420 PQCS(d11) = -420
QCS(3/3)
• Problem : Over-blurring is unavoidable when iteration proceeds
=>how to improve in this paper : converge at fast rate
AQCS(Adaptive QCS)(1/5)
Range from 0 to 1
Estimated form and its eight –neighbors in the same location of BDCT domain
~
~
• Block-Region Classification– For types :
• : flat region
• : horizontal edge region
• : vertical edge region
• : mid-range region
AQCS(Adaptive QCS)(2/5)
Rhv = variance of horizontally difference block / variance of vertically difference block
Rvh = 1/Rhv
Difference = Rhv - Rvh
AQCS(Adaptive QCS)(3/5)
Maximum DCT coefficient
~
AQCS(Adaptive QCS)(4/5)
• Basic idea : change energy before and after projection should be minimal
•Four BS*BS are obtained(four types)
•If is not uniquely determinedMaximum value in case of flat regionMinimum value in other region
AQCS(Adaptive QCS)(5/5)
Experimental Results(1/3)
Experimental Results(2/3)
Experimental Results(3/3)
Conclusion
• Number of Iterations can be reduced ,but Computation time is long => hardware