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伽玛(Gamma)是一个在影视行业经常谈论,但很容易被误解的概念。在影视制作中伽玛无处不在,却又常常被忽略。伽玛很简单,一句话就可以概括描述。伽玛又非常神秘,影视人经常被不同的伽玛特性搞的焦头烂额。狭义的伽玛是电视伽玛校正的简称,是为校正显像管的非线性特性而对视频信号电平进行的非线性处理。广义的伽玛表示系统的灰度(亮度)特性,是拍摄、制作和显示系统的光一电(亮度一编码值)转换特性的总称,影视制作所说的伽玛主要是指拍摄、记录、文件、制作的灰度特性。 相似文献
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在统一通信中,多种通信形式并存,规格、能力不同的各种通信终端参与到通信过程中。在视频通信的情况下,不同终端之间在视频显示的属性方面存在很大差别。那么如何保证通信用户获得最佳的用户体验就非常重要。伽玛特性是决定终端视频用户体验的一个重要因素,因此需要研究一般情况下的伽玛校正问题。但是在统一通信的复杂应用环境中,这个问题的解决也是一个复杂、艰巨的问题。本文拟就这个问题,进行一些分析和探讨。 相似文献
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伽玛值、白场色温及亮度对显示效果的影响 总被引:5,自引:3,他引:2
对Gamma值、白场色温及亮度参数对显示颜色的影响进行了定量的研究。实验结果表明:选择恰当的伽玛值可以改善图像的显示效果;色温的影响大于伽玛值,选择色温值要根据显示器的具体工作环境来决定;亮度对显示效果几乎没有影响,可以根据观察条件来选择。 相似文献
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队列缓存技术在虚拟多道脉冲幅度分析中的应用 总被引:1,自引:0,他引:1
介绍一种在LabVIEW平台下开发虚拟伽玛能谱仪中的实现方案中,为解决数据采集与计算机的脉冲幅度分析之间的运行速度不协调,利用LabVIEW中的队列缓存Queue技术,使核脉冲数据的采集和虚拟多道脉冲幅度分析之间能够达到协调运行,而不会发生丢失数据的现象。此方案体现出一定的优势。 相似文献
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视频通信中的伽玛校正 总被引:2,自引:1,他引:1
视频通因子等)参数外,对于视频,因为各个环节引起的伽玛非线性问题,造成对于亮度信号的失真(Di stortion),也是影响最终用户体验的重要因素.文中提出了在视频通信中伽玛校正的概念、原因、产生的环节以及校正方法. 相似文献
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先验信息的使用是提高雷达目标检测性能的有效途径之一,然而先验信息与当前探测环境的失配会严重影响到检测器的性能.本文考虑逆伽马分布纹理、复合高斯杂波下的知识辅助检测算法,推导了先验模型失配条件下(逆伽马分布参数失配)检测器的虚警率和Swerling I型目标的检测概率计算公式,获得了检测性能与模型参数失配之间的量化关系.利用两组不同参数的知识辅助检测器对当前杂波环境进行探测,通过评估检测器的性能,实现了当前杂波环境模型参数的估计.计算机仿真和实测数据的分析结果表明,采用认知方法的知识辅助检测器较常规检测器而言,能够获得更好的检测性能. 相似文献
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Yasuda K. Niraula M. Noda K. Yokota M. Ohashi H. Nakamura K. Omura M. Shingu I. Minoura S. Tanaka R. Agata Y. 《Electron Device Letters, IEEE》2006,27(11):890-892
Room temperature nuclear radiation detectors with energy discrimination capability developed by growing thick cadmium telluride (CdTe) epitaxial layers directly on n+-Si substrates in a metal-organic vapor phase epitaxy system is reported for the first time. The CdTe/n+-Si heterojunction diode detector exhibited good rectification and charge collection properties. The reverse leakage currents were typically 1times10-7 to 5times10-7 A/cm2 at 50-V bias. The detector clearly demonstrated its energy discrimination capability by resolving gamma peak from the 241Am radioisotope during radiation detection test at room temperature 相似文献
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《Solid-State Circuits, IEEE Journal of》2006,41(9):2188-2192
A peak/RMS power detector with$geq hbox 40~dB$ dynamic range is presented. The simulated frequency response is flat to 60GHz and the measured response is flat to 20 GHz. Analysis shows that the Meyer detector, originally developed as a peak detector, can be used for RMS detection with an error less than 0.5dB over an approximately 20 dB range, comparable to the popular RF/microwave diode detector. The range for RMS detection is extended by cascading several stages of attenuators and detectors, leading to a circuit suitable for applications such as embedded RFIC test. The power detector is only 700$,times,$ 550$muhbox m ^2$ including all AC and DC bond pads. 相似文献
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针对激光半主动导引头四象限探测器对回波窄脉冲信号高精度同步采样需求,设计了一款基于FPGA的四象限探测器信号处理板。该设计主要包括峰值检测模块、触发模块和FPGA模块。探测器前端板输出信号经峰值检测模块自动获取峰值电压后,由ADC实现模数变换,在FPGA内进行目标位置解算并形成制导指令上传至飞控板。其核心设计峰值检测模块,解决了窄脉冲信号峰值捕获的难题。实验表明,该设计输出波形稳定,且输出与输入具有良好的线性关系,最大相对误差小于4,通道一致性高于98,满足四象限探测器读出需求;与现有两款峰值检测模块进行性能对比,表明该设计性能表现良好。 相似文献
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传统的以单片机为核心的多道脉冲幅度分析器集成度低、软硬件设计难度大、系统升级困难。文中介绍了一种以高性能32位嵌入式处理器S3C2440处理为核心的多道脉冲幅度分析器的硬件设计方案,电路主要包括甄别电路、峰值扩展电路、控制电路和A/D转换电路。甄别电路通过设定阈值去除低能噪声信号,峰值检测电路进行输入信号的峰位检测和峰值扩展,A/D转换电路实现输入信号的模拟-数字量的转换。控制电精确控制了整个电路的工作时序。测试表明,该系统具备良好的微分非线性和积分非线性、速度快、稳定性好、可用于实际工作。 相似文献
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M. Niraula K. Yasuda K. Takagi H. Kusama M. Tominaga Y. Yamamoto Y. Agata K. Suzuki 《Journal of Electronic Materials》2005,34(6):815-819
A CdTe/n+-GaAs heterojunction diode for a room-temperature nuclear radiation detector has been developed and demonstrated. The heterojunction
diode was fabricated by growing a 2–5-μm-thick iodine-doped n-CdTe buffer layer on the n+-GaAs substrates, followed by about 100-μm-thick undoped p-like single crystalline CdTe layer using metalorganic vapor-phase
epitaxy. The n-type buffer layer was found to be essential to improve the junction property of the diode detector. The diode
detectors exhibited good rectification property and had the reverse leakage currents typically from 1 μA/cm2 to 5 μA/cm2 at 40 V bias. The detector clearly demonstrated its energy resolution capability by resolving the 59.54-keV gamma peak from
the 241Am radioisotope during the radiation detection test. 相似文献
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Stewart A.G. Saveliev V. Bellis S.J. Herbert D.J. Hughes P.J. Jackson J.C. 《Quantum Electronics, IEEE Journal of》2008,44(2):157-164
A silicon photomultiplier (SPM) is a large area detector consisting of a parallel array of photon counting microcells. Each microcell consists of a Geiger Mode photodiode with an integrated quenching element. Each microcell is then connected to a common output. The microcells have a uniform gain of up to 10 and provide an identical charge output signal for each photon detected. Under illumination the summed output of the detector is proportional to the number of Geiger pulses and hence proportional to the incident photon flux. This combination gives extremely high performance comparable to that of a conventional photomultiplier tube (PMT). We report on the characterization of two different 1 mm2 SPM detector designs with 620 and 920 microcells at room temperature (20 deg) and down to . We assess detection efficiency, breakdown voltage, gain, dark rate, crosstalk, timing jitter and dynamic range. The SPM detector operates over the visible region of the spectrum, characterized here from 400 to 800 nm. The peak photon detection efficiency of 15% occurs at 500 nm with a cooled () dark rate of 600 at a bias voltage of 31 V. In a test for positron emission tomography (PET), an energy resolution of 25% was recorded for the detection of 511 keV gamma radiation using 1 mm1 mm15 mm LYSO scintillator crystal. The SPM has many applications such as medical imaging, microscopy, high-energy physics, and homeland security. 相似文献
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频谱分析仪检波方式的分析与研究 总被引:1,自引:0,他引:1
频谱分析仪是常用的射频测量仪器之一。在测试和分析各种信号时,必须选择合适的检波方式才能正确反映它们的特性,如果选择不合适的检波方式可能会导致测试结果出现误差或者错误。介绍频谱分析仪的多种检波方式,详细分析采样检波、最大峰值检波、最小峰值检波、自动峰值检波、普通检波、平均值检波、均方根检波、准峰值检波的特点和用途,最后总结了各种检波方式的区别。 相似文献