1444 C.-M.Song et aL Signal Processing:Image Communication 28 (2013)1435-1447 Table 3 Average PSNR(dB)of various reconstructed sequences by each algorithm with a block size of 8 x 8 pixels Sequence Bit-rate(kbps】 8BT 1BT MT-2BT AQ-2BT NUQ-2BT FQ-2BT Flower 128 23.29 22.47 22.66 22.73 22.63 22.91 384 23.32 22.49 22.68 22.76 22.66 22.94 500 23.34 22.51 22.70 22.78 22.67 22.96 Football 128 29.91 27.06 28.19 28.35 28.07 28.41 384 29.99 27.09 28.25 28.41 28.09 28.46 500 30.03 27.14 2828 28.45 28.12 28.50 Mobile 128 22.65 21.37 21.73 21.84 22.02 22.05 384 22.68 21.39 21.75 21.87 22.05 22.08 500 22.71 21.41 21.77 21.89 22.07 22.10 Paris 128 25.63 24.02 24.38 24.57 24.82 24.83 384 25.81 2417 24.50 24.74 25.01 25.02 500 26.34 24.24 24.59 24.83 2537 25.41 Stefan 128 24.55 23.06 23.67 23.69 23.79 23.80 384 24.62 23.12 23.72 23.75 23.87 28.89 500 24.67 23.15 23.76 23.80 23.91 23.93 Tennis 128 28.55 25.96 26.99 27.12 26.87 27.07 384 28.65 25.98 26.99 27.17 26.96 27.14 500 28.71 26.03 26.99 27.19 27.03 27.19 Tempete 128 24.95 23.43 23.72 23.88 24.00 24.06 384 25.02 23.48 23.68 23.94 24.05 2410 500 25.08 23.51 23.79 23.98 2410 24.15 City 1024 28.52 25.59 26.36 26.53 2684 26.88 1500 28.58 25.64 26.40 26.59 26.89 26.93 2048 28.68 25.68 26.45 26.66 26.95 27.02 Crew 1024 32.48 28.76 29.86 28.42 30.00 30.01 1500 32.56 28.81 29.91 30.36 30.05 30.07 2048 32.63 28.86 29.99 30.43 30.10 30.15 Harbour 1024 27.25 24.86 25.38 24.99 25.86 25.88 1500 27.30 24.90 25.42 25.79 2591 25.92 2048 27.39 24.95 25.49 25.86 25.97 26.00 Carphone 32 28.77 25.97 26.64 26.87 27.08 27.11 28.88 26.05 26.71 26.99 27.14 27.15 128 29.28 26.19 26.95 27.22 28.14 28.15 Grandma 29.73 26.70 27.87 28.10 28.13 28.23 64 29.95 26.81 28.03 28.30 2833 28.41 128 31.89 2712 28.48 29.03 29.49 30.37 255 29 o 8BT (gp)awey 25 0-1BT 28.5 -MT-2BT 24.5 ￥-AQ-2BT NUQ-2BT 24 -0-FQ-2BT 27.5 25 23 26.5 22.5 26 22 一AQ-2BT 25.5 9NU0-2B1 0-F0-28T 21.5 10 20 3040506070 80 25 2 10 20 30405060 7080 90 Frame Number Frame Number Fig.5.PSNR performance comparison among different motion estima- Fig.6.PSNR performance comparison among different motion estima- tion algorithms for "Flower"at the bit-rate of 500 kbps.The macroblock tion algorithms for "Paris"at the bit-rate of 500 kbps.The macroblock size is16×16 pixels. size is16×16 pixels. Furthermore,MT-2BT uses the variance of a video frame to introducing an adaptive quantization strategy and a uni- complete bit transform.Because the encoder's scalar form threshold for blocks in one search window.AQ-2BT quantization always affects pixels'variance,the bit trans- algorithm improves the bit transform quality and achieves form results tend to be inaccurate.Both the two factors of 0.17 dB higher PSNR than that of MT-2BT.But AQ-2BT does MT-2BT mislead its search for optimum matching block so not take scalar quantization noises into consideration as to degrade the encoder's coding efficiency.Through either.Its hard thresholding technique brings about anFurthermore, MT-2BT uses the variance of a video frame to complete bit transform. Because the encoder's scalar quantization always affects pixels' variance, the bit trans￾form results tend to be inaccurate. Both the two factors of MT-2BT mislead its search for optimum matching block so as to degrade the encoder's coding efficiency. Through introducing an adaptive quantization strategy and a uni￾form threshold for blocks in one search window, AQ-2BT algorithm improves the bit transform quality and achieves 0.17 dB higher PSNR than that of MT-2BT. But AQ-2BT does not take scalar quantization noises into consideration either. Its hard thresholding technique brings about an Table 3 Average PSNR (dB) of various reconstructed sequences by each algorithm with a block size of 8 8 pixels. Sequence Bit-rate (kbps) 8BT 1BT MT-2BT AQ-2BT NUQ-2BT FQ-2BT Flower 128 23.29 22.47 22.66 22.73 22.63 22.91 384 23.32 22.49 22.68 22.76 22.66 22.94 500 23.34 22.51 22.70 22.78 22.67 22.96 Football 128 29.91 27.06 28.19 28.35 28.07 28.41 384 29.99 27.09 28.25 28.41 28.09 28.46 500 30.03 27.14 28.28 28.45 28.12 28.50 Mobile 128 22.65 21.37 21.73 21.84 22.02 22.05 384 22.68 21.39 21.75 21.87 22.05 22.08 500 22.71 21.41 21.77 21.89 22.07 22.10 Paris 128 25.63 24.02 24.38 24.57 24.82 24.83 384 25.81 24.17 24.50 24.74 25.01 25.02 500 26.34 24.24 24.59 24.83 25.37 25.41 Stefan 128 24.55 23.06 23.67 23.69 23.79 23.80 384 24.62 23.12 23.72 23.75 23.87 28.89 500 24.67 23.15 23.76 23.80 23.91 23.93 Tennis 128 28.55 25.96 26.99 27.12 26.87 27.07 384 28.65 25.98 26.99 27.17 26.96 27.14 500 28.71 26.03 26.99 27.19 27.03 27.19 Tempete 128 24.95 23.43 23.72 23.88 24.00 24.06 384 25.02 23.48 23.68 23.94 24.05 24.10 500 25.08 23.51 23.79 23.98 24.10 24.15 City 1024 28.52 25.59 26.36 26.53 26.84 26.88 1500 28.58 25.64 26.40 26.59 26.89 26.93 2048 28.68 25.68 26.45 26.66 26.95 27.02 Crew 1024 32.48 28.76 29.86 28.42 30.00 30.01 1500 32.56 28.81 29.91 30.36 30.05 30.07 2048 32.63 28.86 29.99 30.43 30.10 30.15 Harbour 1024 27.25 24.86 25.38 24.99 25.86 25.88 1500 27.30 24.90 25.42 25.79 25.91 25.92 2048 27.39 24.95 25.49 25.86 25.97 26.00 Carphone 32 28.77 25.97 26.64 26.87 27.08 27.11 64 28.88 26.05 26.71 26.99 27.14 27.15 128 29.28 26.19 26.95 27.22 28.14 28.15 Grandma 32 29.73 26.70 27.87 28.10 28.13 28.23 64 29.95 26.81 28.03 28.30 28.33 28.41 128 31.89 27.12 28.48 29.03 29.49 30.37 Fig. 5. PSNR performance comparison among different motion estima￾tion algorithms for “Flower” at the bit-rate of 500 kbps. The macroblock size is 16 16 pixels. Fig. 6. PSNR performance comparison among different motion estima￾tion algorithms for “Paris” at the bit-rate of 500 kbps. The macroblock size is 16 16 pixels. 1444 C.-M. Song et al. / Signal Processing: Image Communication 28 (2013) 1435–1447