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An Improved H.264 Encoded Algorithm Based on Weber-Fechner Law
Yanhui Xia,Baisheng Nie,Zhengyou Wang,Liying Li,Jianhua Ming,Zheng Wan,Shuying Huang 보안공학연구지원센터 2015 International Journal of Multimedia and Ubiquitous Vol.10 No.9
With the study of human visual system (HVS), people find that the human eye shows different degree of sensitivity to different light signals. A higher background brightness region of the human eye for the distortion, the degree of sensitivity will be greatly reduced. The human eye’s sensitivity will be greatly reduced to the distortion of a higher brightness background region. This finding is discribed in Weber-Fechner law. Therefore, the encoder can be improved by employing this characteristic of human visual system. In this paper, the authors use this characteristic to improve the H.264 video coding algorithm. In order to improve the compression efficiency of encoder, give the brightness of different regions with different levels of quantification by adjusting the quantization step size (QP), without affecting the subjective quality of video. Experimental results show that the output bit rate decrease up to 10% -20% by using this improved algorithm in H.264 reference encoder, and the subjective quality of decoded image by using this improved algorithm is as good as the standard H.264 encoders.
A New Image Quality Assessment Algorithm based on SSIM and Multiple Regressions
Zhengyou Wang,Liying Li,Shuang Wu,Yanhui Xia,Zheng Wan,Cong Cai 보안공학연구지원센터 2015 International Journal of Signal Processing, Image Vol.8 No.11
Image quality assessment (IQA) is crucial in image processing algorithms. In the state-of-the-art IQA index, the structural similarity (SSIM) index has been proved to be better objective quality assessment metric. However, the accuracy of SSIM is relatively lacking when used to access blurred images. And the component weights of structural similarity (SSIM) index are fixed in some past environments. So an improved assessment algorithm incorporating multiple linear regressions and SSIM index was proposed in this paper. We use regression analysis to adjust the component weight of SSIM index. So the improved algorithm is more accuracy on different distortion types’ quality assessment. Experimental results show that the improved SSIM algorithm is better than traditional methods in nonlinear regression correlation coefficient, Spearman correlation coefficient and out ratio.
Xiaokun Hu,Qiangqiang Zhao,Yitao Yang,Shaoke Wan,Yanhui Sun,Jun Hong 한국CDE학회 2023 Journal of computational design and engineering Vol.10 No.5
The rotation accuracy of a machine tool spindle is essential for ensuring the machining precision. Due to the existence of manufacturing and assembly errors, the rotation accuracy of the spindle will be inevitably impacted and degraded. Therefore, to reduce the influence of the errors and improve the work performance, this paper focuses on accuracy analysis for the spindle and a novel optimization-oriented skin model shape method to tackle this highly complex problem. First, a structural analysis of the spindle is carried out to elaborate the intractable full parallel collections in the assembly. Then, based on the iterative closest point method, the deviation propagation of the spindle considering complex full parallel collections is transformed into an optimization problem, in which the skin model shapes and small displacement torsor are utilized to represent the form and pose errors of the part, respectively. By solving the optimization problem, assembly accuracy analysis for the spindle in terms of full parallel connections and form errors is accordingly achieved. On this basis, the tolerance analysis model of the spindle is also comprehensively established by employing the corresponding error simulation. Finally, measurement experiments are conducted to validate the effectiveness of the proposed method. The experiments show the predicted rotation runout and tolerance magnitude are close to the testing results, therefore indicating the proposed method can provide effective accuracy analysis for spindles.