An efficient Video Coding using Phase-matched Error from Phase Correlation Information Manoranjan Paul 1 and Golam Sorwar 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 block e: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 , 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 k H (3N 2 (2d+1) 2 ), k H :average modes per MB – Proposed technique k P (3N 2 (2d+1) N 2 ) (k H - k P )/k H : 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.