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基于无参考结构清晰度的自适应自动对焦方法 被引量:18
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作者 谢小甫 周进 吴钦章 《光电工程》 CAS CSCD 北大核心 2011年第2期84-89,共6页
针对自动对焦系统,提出了一种基于单帧图像无参考结构清晰度的自适应变步长爬山搜索策略。该方法利用了无参考结构清晰度可提供的离焦量先验信息:当离焦量大时,大步距粗调快速逼近准焦位置;当离焦量小时,小步距微调准确定位准焦位置。... 针对自动对焦系统,提出了一种基于单帧图像无参考结构清晰度的自适应变步长爬山搜索策略。该方法利用了无参考结构清晰度可提供的离焦量先验信息:当离焦量大时,大步距粗调快速逼近准焦位置;当离焦量小时,小步距微调准确定位准焦位置。该方法在不降低调焦精度的情况下,大大减少了自动对焦所需的图像数量和决策次数。实际系统实验结果表明,新方法使自动对焦速度提高了50%以上。 展开更多
关键词 自动对焦 对焦函数 爬山搜索法 无参考结构清晰度
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一种针对图像模糊的无参考质量评价指标 被引量:59
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作者 谢小甫 周进 吴钦章 《计算机应用》 CSCD 北大核心 2010年第4期921-924,共4页
在成像模型的基础上,分析了图像模糊的原因,提出了一种为图像构造参考图像的方法,进而将结构相似度(SSIM)评价方法引入到无参考图像质量评价中,提出一种无参考结构清晰度(NRSS)的新的无参考图像质量评价方法,将其用于对模糊图像的质量... 在成像模型的基础上,分析了图像模糊的原因,提出了一种为图像构造参考图像的方法,进而将结构相似度(SSIM)评价方法引入到无参考图像质量评价中,提出一种无参考结构清晰度(NRSS)的新的无参考图像质量评价方法,将其用于对模糊图像的质量评价。该方法通过低通滤波器来构造参考图像,通过计算原始图像与参考图像的结构相似度值来评价原始图像质量,很好地结合了成像系统的数学模型和结构相似度评价方法的优势,实验结果表明无参考结构清晰度评价指标能够给出和主观评价方法以及其余有参考评价方法一致的结果。 展开更多
关键词 图像质量评价 成像模型 结构相似度 无参考结构清晰度 梯度能量函数
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影响图式归纳和类比迁移的三因素实验研究 被引量:11
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作者 邱琴 胡竹菁 闵容 《心理科学》 CSSCI CSCD 北大核心 2005年第6期1370-1374,共5页
该研究探讨被试的认知风格、源问题结构的清晰度及两个源问题间内容的相似性三者对图式归纳和类比迁移的影响。实验采用2×2×2的三因素完全随机设计。结果显示:(1)源问题图式表征的质量受到被试认知风格和源问题结构的清晰度... 该研究探讨被试的认知风格、源问题结构的清晰度及两个源问题间内容的相似性三者对图式归纳和类比迁移的影响。实验采用2×2×2的三因素完全随机设计。结果显示:(1)源问题图式表征的质量受到被试认知风格和源问题结构的清晰度两个变量的影响;(2)类比迁移的成绩只受到源问题结构清晰度的影响;(3)结构清晰的条件下,两类被试图式表征的质量无明显差异;结构不清晰的条件下,两类被试图式表征的质量出现明显差异。 展开更多
关键词 图式归纳 类比迁移 结构清晰度 图式表征
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基于相邻像素差与NRSS的自动对焦算法 被引量:4
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作者 陈浩 陈健 +1 位作者 叶轻舟 蔡志明 《计算机工程》 CAS CSCD 北大核心 2015年第9期261-265,共5页
针对传统无参考模糊图像质量评价算法实时性和有效性较差的问题,在改进无参考结构清晰度(NRSS)算法的基础上,结合相邻像素差,提出一种应用于自动对焦的无参考图像清晰度评价算法。利用最邻近重采样法对原始图像进行预处理,分别计算原始... 针对传统无参考模糊图像质量评价算法实时性和有效性较差的问题,在改进无参考结构清晰度(NRSS)算法的基础上,结合相邻像素差,提出一种应用于自动对焦的无参考图像清晰度评价算法。利用最邻近重采样法对原始图像进行预处理,分别计算原始图像的NRSS和相邻像素差清晰度(APDS),并将2个清晰度加权求和得到图像最终的清晰度。仿真实验结果表明,与APDS和NRSS算法相比,该算法运算速度更快,且评价结果与主观评价结果具有更高的一致性。 展开更多
关键词 自动对焦 清晰度评价函数 图像质量评价 均值滤波 无参考结构清晰度算法
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Highly parallel implementation of sub-pixel interpolation for AVS HDTV decoder 被引量:2
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作者 Wan-yi LI Lu YU 《Journal of Zhejiang University-Science A(Applied Physics & Engineering)》 SCIE EI CAS CSCD 2008年第12期1638-1643,共6页
In this paper, we propose an effective VLS1 architecture of sub-pixel interpolation for motion compensation in the AVS HDTV decoder. To utilize the similar arithmetical operations of 15 luma sub-pixel positions, three... In this paper, we propose an effective VLS1 architecture of sub-pixel interpolation for motion compensation in the AVS HDTV decoder. To utilize the similar arithmetical operations of 15 luma sub-pixel positions, three types of interpolation filters are proposed. A simplified multiplier is presented due to the limited range of input in the chroma interpolation process. To improve the processing throughput, a parallel and pipelined computing architecture is adopted. The simulation results show that the proposed hardware implementation can satisfy the real-time constraint for the AVS HDTV (1 920× 1 088) 30 fps decoder by operating at 108 MHz with 38.18k logic gates. Meanwhile, it costs only 216 cycles to accomplish one macroblock, which means the B frame sub-pixel interpolation can be realized by using only one set of the proposed architecture under real-time constraints. 展开更多
关键词 VLSI architecture INTERPOLATION AVS HDTV
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Experimental and Numerical Study of Wind Noise Caused by Cowl Area on Volvo XC60
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作者 Olga Roditcheva Par Harling +1 位作者 Dragos Moroianu Holger Bemhardsson 《Journal of Mechanics Engineering and Automation》 2016年第3期109-117,共9页
This paper presents a detailed experimental and numerical study of aerodynamically produced noise which occurs due to turbulent structures created by the cowl cavity and side mirror. Measurements were carried out at V... This paper presents a detailed experimental and numerical study of aerodynamically produced noise which occurs due to turbulent structures created by the cowl cavity and side mirror. Measurements were carried out at Volvo aerodynamical wind tunnel on a Volvo XC60 production model. The configurations considered here are: side mirror On/Off with the cowl cavity open/closed. The results of exterior sound source mapping (with the intensity probe placed in the flow stream) have been compared with the results of the measurements inside the car. The contribution of the cowl area to overall wind noise level is measured in terms of AI% (Articulation Index) inside the compartment. It was shown that increase in AI by 2% could be attributed to the cowl generated wind noise. Transient numerical simulations of the turbulent flow around the car have been performed for all configurations. The results of the simulations show similarity to experimental results and give insight to the flow structures around the car. 展开更多
关键词 Aerodynamically produced noise wind noise turbulent flow experimental and numerical methods for aeroacoustics sound sources ground vehicles.
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Application of deep-towed multichannel seismic system for gas hydrate on mid-slope of northern Cascadia margin 被引量:2
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作者 KONG FanDa HE Tao George D.SPENCE 《Science China Earth Sciences》 SCIE EI CAS 2012年第5期758-769,共12页
The Deep-towed Acoustics and Geophysics System (DTAGS) is a high frequency (220-820 Hz) multichannel seismic system towed about 300 m above seafloor.Compared to the conventional surface-towed seismic system,the DTAGS ... The Deep-towed Acoustics and Geophysics System (DTAGS) is a high frequency (220-820 Hz) multichannel seismic system towed about 300 m above seafloor.Compared to the conventional surface-towed seismic system,the DTAGS system is characterized by its shorter wavelength (<6 m),smaller Fresnel zone,and greater sampling in wavenumber space,so it has unique advantages in distinguishing fine sedimentary layers and geological structures.Given the near-bottom configuration and wide high-frequency bandwidth,the precise source and hydrophone positioning is the basement of subsequent seismic imaging and velocity analysis,and thus the quality of array geometry inversion is the key of DTAGS data processing.In the application of exploration for marine gas hydrate on mid-slope of northern Cascadia margin,the DTAGS system has shown high vertical and lateral resolution images of the sedimentary and structural features of the Cucumber Ridge (a carbonate mound) and Bullseye Vent (a cold vent),and provided abundant information for the evaluation of gas hydrate concentration and the mechanism of fluid flow that controls the formation and distribution of gas hydrate. 展开更多
关键词 deep-towed multichannel seismic system slope of northern Cascadia margin marine gas hydrate carbonate mound cold vent
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Parallel processing architecture of H.264 adaptive deblocking filters 被引量:1
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作者 Hu WEI Tao LIN Zheng-hui LIN 《Journal of Zhejiang University-Science A(Applied Physics & Engineering)》 SCIE EI CAS CSCD 2009年第8期1160-1168,共9页
In H.264,computational complexity and memory access of deblocking filters are variable,dependent on video contents.This paper proposes a VLSI architecture of deblocking filters with adaptive dynamic power,which avoids... In H.264,computational complexity and memory access of deblocking filters are variable,dependent on video contents.This paper proposes a VLSI architecture of deblocking filters with adaptive dynamic power,which avoids redundant computations and memory accesses by precluding the blocks that can be skipped.The vertical and horizontal edges are simulta-neously processed in an advanced scan order to speed up the decoder.As a result,dynamic power of the proposed architecture can be reduced adaptively(up to about 89%) for different videos,and the off-chip memory access is improved when compared to previous designs.Moreover,the processing capability of the proposed architecture is in particular appropriate for real-time deblocking of high-definition television(HDTV,1920×1080 pixels/frame,60 frames/s video signals) video operation at 62 MHz.Using the proposed architecture,power can be reduced by up to about 89% and processing time by from 25% to 81% compared with previous designs. 展开更多
关键词 Deblocking filter Adaptive dynamic power Parallel processing PIPELINE H.264
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