共查询到20条相似文献,搜索用时 484 毫秒
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具备亮度校正功能的DVI-DVI处理器被应用到LED大屏幕显示,可以较好的解决工程上为了增加或升级亮度校正功能而更换显示控制系统的问题.但是DVI-DVI处理器的动态内存读取频率较低,不能发挥DVI双链路的数据传输性能.本文通过对动态内存中待读取的校正参量按照特定算法进行重组和压缩,将动态内存的等效读取频率从266MHz提高到330MHz,实现DVI双链路传输对超大分辨率的LED显示屏进行有效的亮度校正. 相似文献
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文章对液晶电视亮度感应自动控制存在的问题进行了深入探讨,并提出了对应的改进和防范措施.通过亮度感应器,采集到周围环境的亮度;进行多次采样自动校正算法,减少外界环境亮度变化的干扰,得到稳定的亮度;通过模拟迟滞比较算法,减少亮度忽亮忽暗的变化,设定稳定的控制液晶面板背光的脉宽调制信号;由脉宽调制信号对液晶而板背光进行调整得... 相似文献
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条纹非均匀性是线扫红外焦平面阵列和非制冷凝视型红外焦平面阵列成像系统中一种特殊的固定图案噪声.分析了其产生的原因,提出了一种基于亮度恒定假设和配准的条纹非均匀性校正算法.根据相邻两帧获得亮度均方误差函数,最后通过最小化全局亮度均方误差函数得到全局最优解作为非均匀性校正的参数.实验结果表明,该算法能够在几帧内达到较好的收... 相似文献
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宽幅CCD相机的输出非均匀性校正对获取高质量的遥感图像具有重要意义。通过分析造成CCD输出非均匀的原因,提出了基于辐射亮度反演的非均匀性线性校正概念。在已知的多种辐亮度照明下,采集相机每个像素的灰度值,利用最小二乘法建立像元灰度值与辐亮度的函数,求出像元的两项非均匀性校正系数——暗信号与响应度。实验结果表明:利用这两项校正系数进行相机非均匀性校正,改善效果明显。校正前图像的灰度值均方根偏差为1.3%,校正后为0.2%;从图像上看,校正前图像上的明暗条纹很明显,校正后得到消除。不仅如此,采用该校正方法还能够有效去除通道间输出非均匀性造成的整幅拼接图像的明暗不一致,得到均匀清晰的图像,结果令人满意。 相似文献
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对曝光不足的图像和视频进行亮度调整具有重要的理论研究意义和实际应用价值,本文提出一种基于梯度域操作的图像和视频亮度自动调整算法.对于静态图像,算法首先将图像分割为不同的亮度区域;然后分别计算各区域的亮度调整算子;最后通过求解一个梯度约束方程得到结果图像.我们进而将该算法延伸到视频,首先选取若干关键帧并使用上述图像亮度调整算法进行处理;然后对非关键帧进行分割并通过光流算法确定非关键帧上的分割区域与前后关键帧区域的对应关系;最后利用对应关系通过关键帧区域的亮度调整算子以及调整后的亮度指导非关键帧上各区域的亮度调整,并生成结果视频序列.本文算法可以有效处理空间和时间上曝光不足和不均的图像和视频,并能够较好地保持图像、视频的细节纹理信息,实验结果表明了算法的有效性. 相似文献
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带有亮度逐点校正技术的LED屏更换点或模块后,需要修复全屏亮度一致性,针对其修复过程提出了一种局部亮度校正参量修正算法.采用该算法可快速计算出替换点或模块一致化校正参量,避免对全屏的重新校正.首先分析替换点像素的修正算法并更换模块的各个像素点的修正算法;然后通过PC机端软件定位处理点或模块,完成对更新点、模块的校正参量的局部修正过程;最后,利用该局部修正算法完成对LED显示屏亮度的一致化修正.经实测验证,局部修正方法与标准化方法在更新时间上,前者更快速和简便,且应用环境更广泛. 相似文献
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本文提出了一种有效的基于亮度保持对比度增强算法.利用BBHE(brightness preserving bi-histogram equalization)算法产生的两个子图像,对两个子图像进行加权求和,从而得到输出图像.同时,根据输入图像以及两个子图像的亮度均值,给出了一种基于亮度保持的权重系数的计算方法.实验结果表明,与其它亮度保持对比度增强算法相比,本文算法能够更准确地保持输入图像的亮度均值以及较好地实现对比度增强.另外,本文算法计算简单,能够满足实时性的要求. 相似文献
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《IEEE transactions on circuits and systems. I, Regular papers》2006,53(10):2157-2166
This paper presents a low-supply voltage integrated CMOS voltage-controlled oscillator (VCO) with an on-chip digital VCO calibration control system. The VCO utilizes various state-of-the-art design methods to achieve low phase noise. The calibration system includes a novel high-speed digital divide by two circuit and a counter running on 1-GHz input to enable on-chip frequency measurement. An arithmetic unit and algorithms to perform the calibration are implemented using on-chip logic. Two different types of calibration methods have been implemented and measured in order to compare the proposed VCO gain optimization method with more conventional type of VCO calibration. The measurements show that the VCO design has phase noise from$-$ 120.5 dBc/Hz to$-$ 118.7 dBc/Hz @ 400-kHz offset, measured over the frequency range from 1.67 to 1.93 GHz. The proposed VCO gain optimization method is capable of reducing the$K_ VCO$ peak-to-peak variation of the presented VCO design from 54.4% to 29.8% in DCS1800 and PCS1900 GSM transmission bands when compared to the conventional type of calibration method. 相似文献
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This work describes two algorithms designed for remote calibration of an Nc-element active phased-array antenna. These algorithms involve transmission of N⩾Nc time multiplexed orthogonal encoded signals. The received signals are coherently detected, accumulated in vector forms, and decoded with the inverse of the orthogonal encoding matrix. The unitary transform encoding (UTE) algorithm is most suited for digital beamforming as it requires additional encoding hardware for an analog implementation. The control circuit encoding (CCE) algorithm is ideally suited for analog beamformers as it requires no additional encoding hardware. The CCE method encodes phased-array elemental signals using a Hadamard matrix to control the switching of intrinsic phase shifter delay circuits. The UTE and CCE algorithms can reduce the average measurement integration times for the complete set of calibration parameters by ~Nc relative to the corresponding values for single-element calibration procedures. This is significant for satellite systems as calibration must be performed in a short enough time window that the process can be treated as being stationary. Proofs are given that the orthogonal codes satisfy the mathematical lower bounds for the asymptotic forms of calibration parameter estimation variances 相似文献
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Mohammad Fardad Javad Frounchi Ghader Karimian 《Analog Integrated Circuits and Signal Processing》2012,70(3):347-356
In this paper, a digital processor is presented for full calibration of pipeline ADCs. The main idea is to find an inverse
model of ADC errors by using small number of the measured codes. This approach does not change internal parts of the ADC and
most known errors are compensated simultaneously by digital post-processing of the output bits. Some function approximation
algorithms are tested and their performances are evaluated. To verify the algorithms, a 12-bit pipelined ADC based on 1.5-bit
per stage architecture is simulated with 1%-2% non-ideal factors in the SIMULINK with a 20 MHz sinusoidal input and a 100 MS/s
sampling frequency. The selected algorithm has been implemented on a Virtex-4 LX25 FPGA from Xilinx. The designed processor
improves the SNDR from 45 to 69 dB and increases the SFDR from 45.5 to 90 dB. The calibration processor also improves the
integral nonlinearity of the ADC. 相似文献
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介绍了一种改进的流水线模数转换器(ADC)数字校准算法,该算法使用了一个低速高精确度的参考ADC,同时结合了变步长的最小均方误差(LMS)滤波器校正流水线ADC的误差,从而提高校准速度和精确度。使用Verilog HDL语言设计了这种后台数字校准算法的寄存器传输级(RTL)电路,同时采取Simulink和Modelsim联合仿真的方法对电路进行验证。验证结果表明,与固定步长的校准算法相比,改进的校准算法拥有更快的收敛速度和更高的收敛精确度。 相似文献
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Hsiang-Hui Chang Jung-Yu Chang Chun-Yi Kuo Shen-Iuan Liu 《Solid-State Circuits, IEEE Journal of》2006,41(5):1051-1061
A 0.7-2-GHz precise multiphase delay-locked loop (DLL) using a digital calibration circuit is presented. Incorporating with the proposed digital calibration circuit, the mismatch-induced timing error among multiphase clocks in the proposed DLL can be self-calibrated. When the calibration procedure is finished, the digital calibration circuit can be turned off automatically to save power dissipations and reduce noise generations. A start controlled circuit is proposed to enlarge the operating frequency range of the DLL. Both the start-controlled circuit and the calibration circuit require an external reset signal to ensure the correctness of the calibration after temperature,operating frequency, and power supply voltage are settled. This DLL with the digital calibration circuit has been fabricated in a 0.18-/spl mu/m CMOS process. The measured results show the DLL exhibits a lock range of 0.7-2 GHz while the peak-to-peak jitter and rms jitter is 18.9ps and 2.5 ps at 2 GHz, respectively. When the calibration procedure is completed and the DLL operates at 1 GHz, the maximum mismatch-induced timing error among multiphase clocks is reduced from 20.4 ps (7.34 degree) to 3.5 ps (1.26 degree). 相似文献
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《IEEE transactions on circuits and systems. I, Regular papers》2009,56(2):294-306
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Boussakta S. Alshibami O.H. Aziz M.Y. 《Signal Processing, IEEE Transactions on》2001,49(12):3145-3156
The discrete Hartley transform (DHT) has proved to be a valuable tool in digital signal/image processing and communications and has also attracted research interests in many multidimensional applications. Although many fast algorithms have been developed for the calculation of one- and two-dimensional (1-D and 2-D) DHT, the development of multidimensional algorithms in three and more dimensions is still unexplored and has not been given similar attention; hence, the multidimensional Hartley transform is usually calculated through the row-column approach. However, proper multidimensional algorithms can be more efficient than the row-column method and need to be developed. Therefore, it is the aim of this paper to introduce the concept and derivation of the three-dimensional (3-D) radix-2 × 2 × 2 algorithm for fast calculation of the 3-D discrete Hartley transform. The proposed algorithm is based on the principles of the divide-and-conquer approach applied directly in 3-D. It has a simple butterfly structure and has been found to offer significant savings in arithmetic operations compared with the row-column approach based on similar algorithms 相似文献
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We have developed two new algorithms for the measurement of blood flow from dynamic X-ray angiographic images. Both algorithms aim to improve on existing techniques. First, a model-based (MB) algorithm is used to constrain the concentration-distance curve matching approach. Second, a weighted optical flow algorithm (OP) is used to improve on point-based optical flow methods by averaging velocity estimates along a vessel with weighting based on the magnitude of the spatial derivative. The OP algorithm was validated using a computer simulation of pulsatile blood flow. Both the OP and the MB algorithms were validated using a physiological blood flow circuit. Dynamic biplane digital X-ray images were acquired following injection of iodine contrast medium into a variety of simulated arterial vessels. The image data were analyzed using our integrated angiographic analysis software SARA to give blood flow waveforms using the MB and OP algorithms. These waveforms were compared to flow measured using an electromagnetic flow meter (EMF). In total 4935 instantaneous measurements of flow were made and compared to the EMF recordings. It was found that the new algorithms showed low measurement bias and narrow limits of agreement and also out-performed the concentration-distance curve matching algorithm (ORG) and a modification of this algorithm (PA) in all studies. 相似文献