Post on 23-Feb-2016
description
An efficient Video Coding using Phase-matchedError from Phase Correlation Information
Manoranjan Paul1 and Golam Sorwar2
2008 IEEE
Outline• Introduction• Propose technique– Phase correlation– Binary Matrix Generation using Phase Correlation– Mode Selection from the Binary Matrix
• Computational complexity• Simulation results• Conclusion
Introduction• Variable block size motion estimation and
compensation in H.264. How to choose mode?(RDO)
• Some Fast mode selection mode sacrifice some quality or increase bit streams to reduce computation time.
• Here we advise a algo. using phase correlation technique to predict block size saving 50% time without degrading the image quality.
Phase correlation• In image processing, phase correlation is a method of image
registration, and uses a fast frequency-domain approach to estimate the relative translative offset between two similar images.
Example:
• To obtain the Phase Correlation of two images, perform these steps:
1. DFT:2. cross power spectrum:3. IDFT:4. Determine the location of the peak in
Phase correlation
two motions
one motion no motion
(5,6)
(5,7)(6,5)
Binary Matrix Generation using Phase Correlation
• Phase-matched error 1. )2. )3. )4. )5. ) r:reference bolck, c:current blocke:phase-mached error
Binary Matrix Generation using Phase Correlation
[13] To L., M. Pickering, M. Frater, and J. Arnold, “A motion confidence measure from phase information,” IEEE International Conference on Image Processing, pp. 2583-2586, 2004.
Binary Matrix Generation using Phase Correlation
• The ratio D represents the proportion of energy in the lower-frequency components.
6. )
7. )
Binary Matrix Generation using Phase Correlation
T=0.3 green blocks (8x8 pixels) indicate motion and other areas indicate no motion.
Mode Selection from the Binary Matrix
• The resolution of an image is HxW pixels.• The size of the binary matrix will be H/8xW/8.• 16x16-pixel block is considered as a video
encoding processing unit, thus we will get four sub-blocks.
Based on the binary matrix, we will decide which mode it would be for ME&MC.
Mode Selection from the Binary Matrix
(a)&(b)proposed technique (c)&(d)H.264 cyan,green, blue, and red color for 16x16, 16x8, 8x16, and 8x8 and others respectively.
Computational Complexity• Full search motion estimation using d width
search length.– H.264 kH(3N2(2d+1)2) , kH :average modes per MB – Proposed technique kP(3N2(2d+1)2+5.25N2)
• (kH- kP)/kH : result half number modes per MB at middle range of bit rates.
Simulation results
Conclusion & Future Work• We proposed a video coding technique using phase
correlation information to select motion estimation and compensation modes, and reduces around 50% computational time without losing any image quality compared to the H.264.
• In furture search, using phase correlation to generate
motion vector and seeing the effect of threshold on different bit rates is necessary.