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Region-of-Interest Based H.264 Encoding Parameter Allocation for Low Power Video Communication. M. Wang, T. Zhang, C. Liu and S. Goto CSPA 5th International Colloquium on Signal Processing & Its Applications, 2009. Advisor: 葉家宏 Presenter: 陳詠霖 Date:2010/01/13. Outline. Introduction
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Region-of-Interest Based H.264 Encoding Parameter Allocation for Low Power Video Communication M. Wang, T. Zhang, C. Liu and S. Goto CSPA 5th International Colloquium on Signal Processing & Its Applications, 2009 Advisor:葉家宏 Presenter:陳詠霖 Date:2010/01/13
Outline • Introduction • System Architecture • ROI Detector • Experimental Result • Conclusion
Introduction • H.264 performs an extremely high compression rate and high visual quality • H.264 has huge computation on motion estimation
Introduction • Human eyes only focus on certain object or area, rather than whole frame. • ROI (Region of Interest) • texture contrast, skin color
Introduction • Unequally Encoding • ROI allocated small QP, higher search range, higher reference frame • Non-ROI allocated higher QP, small search range, small reference frame
Outline • Introduction • System Architecture • ROI Detector • Experimental Result • Conclusion
Outline • Introduction • System Architecture • ROI Detector • Experimental Result • Conclusion
ROI Detector • Y channel • Saliency Map • Human vision is more sensitive on a certain spatial spectrum • Band-pass mask • Gaussian mask
ROI Detector • Stripes on the wall are always omitted by eyes
Skin Color Map (UV Channel) • u(i,j) and v(i,j) are U,V components of the pixel at (i,j) • Lu, Hu, Lv, Hv, Luv, Huv are thresholds of the corresponding various • α=0.6,Lu=97, Hu=118, Lv=138, Hv=163, Luv=198, Huv=207
Greedy Algorithm • Parameter • L :length • A :sum of saliency skin oriented saliency point • TH :shrink ratio threshold • A*TH :saliency sum of ROI
Greedy Algorithm • Border of image (top, bottom, left, right) • Step 1. Shifts L length • Step 2. Surplus saliency points ≦ A*TH • Step 3. Intersect four border
Outline • Introduction • System Architecture • ROI Detector • Experimental Result • Conclusion
Experimental Result • The QP of ROI and non-ROI are set to QPr and QPn. QPr = QP-1 ; QPn = QP+3;
Experimental Result • QP=32,MRF=5/1(ROI/NON-ROI) SEARCH RANGE=32/8(ROI/NON-ROI)
Outline • Introduction • System Architecture • ROI Detector • Experimental Result • Conclusion
Conclusion • ROI based parameter allocation is proposed to avoid unnecessary computation • ROI detection can decreases motion estimation time about 65% time • The proposed algorithm keeps visual quality in the ROI