高动态范围图像算法的高校管理研究

尽管iCAM06算法适合处理动态范围较大的图像;但却损耗了一定的准确性。文中采用小波变换的方式对图像进行分层处理。经实验对比,设计算法针对性地解决了iCAM06算法中的问题,对动态范围小的图像同样具有良好的处理效果,并且成果避免了光晕现象,取得了令人满意的效果。算法在iCAM06算法的基础上实现改进,用以显示高动态图像。这一研究对于实现高校管理的高动态范围监控具有一定的意义。     

An adaptive morphological filter for image processing

Novel types of opening operator (NOP) and closing operator (NCP) are proposed. An adaptive morphological filter is then constructed on the basis of the NOP and NCP. The filter can remove any details consisting of fewer pixels than a given number N, while preserving the other details. Efficient algorithms are also developed for the implementation of the NOP and NCP.     

Arrayed waveguide dynamic gain equalization filter with reducedinsertion loss and increased dynamic range

We present an arrayed waveguide dynamic gain equalization filter with less than 4.5-dB insertion loss and greater than 14-dB dynamic range over the C-band resulting from three improvements: a circulator and polarization splitter combined into one, used to make the device polarization insensitive; segmentation in the star coupler transition regions; and an exponential control wavelength distribution     

Enhanced dynamic range analog filter topologies with a notch/all-pass circuit example

The signal handling capability of the filters is called dynamic range. In this paper, a topological form for the synthesis of filters with high dynamic range is proposed. A biquad notch/all-pass filter is shown in conformity with the given topological form. It is shown that there is a trade-off between dynamic range and high input impedance property. The presented circuit is compared with other notch filters in the literature. It has less number of components, better high-frequency response and dynamic range compared to others. Since the circuit includes a minimum number of resistors, it can easily provide electronically tunable circuits through resistor/controlled current conveyor replacement. Simulations are performed to verify the theoretical results. Routh-Hurwitz stability analyses are also given.     

A fast image super-resolution algorithm using an adaptive Wiener filter.

A computationally simple super-resolution algorithm using a type of adaptive Wiener filter is proposed. The algorithm produces an improved resolution image from a sequence of low-resolution (LR) video frames with overlapping field of view. The algorithm uses subpixel registration to position each LR pixel value on a common spatial grid that is referenced to the average position of the input frames. The positions of the LR pixels are not quantized to a finite grid as with some previous techniques. The output high-resolution (HR) pixels are obtained using a weighted sum of LR pixels in a local moving window. Using a statistical model, the weights for each HR pixel are designed to minimize the mean squared error and they depend on the relative positions of the surrounding LR pixels. Thus, these weights adapt spatially and temporally to changing distributions of LR pixels due to varying motion. Both a global and spatially varying statistical model are considered here. Since the weights adapt with distribution of LR pixels, it is quite robust and will not become unstable when an unfavorable distribution of LR pixels is observed. For translational motion, the algorithm has a low computational complexity and may be readily suitable for real-time and/or near real-time processing applications. With other motion models, the computational complexity goes up significantly. However, regardless of the motion model, the algorithm lends itself to parallel implementation. The efficacy of the proposed algorithm is demonstrated here in a number of experimental results using simulated and real video sequences. A computational analysis is also presented.     

Polyphase adaptive filter banks for fingerprint image compression

A perfect reconstruction polyphase filter bank structure is presented in which the filters adapt to the changing input conditions. The use of such a filter bank leads to higher compression results for images containing sharp edges such as fingerprint images     

大动态范围下的热像显示

在热成像系统中,存在信号源动态范围大,而显示输出动态范围小的矛盾。解决此问题的办法：一是使用笮对立佃和偏移实现人机分离;二是使用信号压缩,保证最大限度地显示所需信息。在介绍了Ｉ类３２元和ＩＩ类ＳＰＲＩＴＥ组件热像仪的大动态范围下热像显示的基础上,提出了高位采样直方图压缩的方法。通过对这几种方法的分析比较,认为第一种方法面对图像且计算量大;而文中的方法面对目标且具有较宽的动态范围,如果需要对目标作进     

Wide dynamic range CMOS image sensor with pixel level ADC

A new enhanced dynamic range (DR) and signal-to-noise ratio (SNR) CMOS imaging system with a pixel level analogue-to-digital converter (ADC) is presented. The proposed reset technique and time-to-digital converter increases DR and peak SNR simultaneously. The circuit reuse concept is also proposed to increase the fill factor.     

改进自适应中值滤波的瓷砖图像降噪

瓷砖自动分类是机器视觉的一大应用,要求有较高的实时性和准确性。图像识别是关键,考虑到现场的实际情况,图像滤波很重要,既要去除噪声,又要保留图像细节。常用滤波方法破坏了图像细节,识别率低,文中在排序自适应中值滤波算法的基础上,引入了最小灰度差,避免将高频细节信号误判为噪声。实验结果对比表明,改进的自适应中值滤波算法在去除高密度噪声与保留细节上都有改善,较大地提高了瓷砖自动分类准确率。     

High dynamic range video reconstruction from a stereo camera setup

To overcome the dynamic range limitations in images taken with regular consumer cameras, several methods exist for creating high dynamic range (HDR) content. Current low-budget solutions apply a temporal exposure bracketing which is not applicable for dynamic scenes or HDR video. In this article, a framework is presented that utilizes two cameras to realize a spatial exposure bracketing, for which the different exposures are distributed among the cameras. Such a setup allows for HDR images of dynamic scenes and HDR video due to its frame by frame operating principle, but faces challenges in the stereo matching and HDR generation steps. Therefore, the modules in this framework are selected to alleviate these challenges and to properly handle under- and oversaturated regions. In comparison to existing work, the camera response calculation is shifted to an offline process and a masking with a saturation map before the actual HDR generation is proposed. The first aspect enables the use of more complex camera setups with different sensors and provides robust camera responses. The second one makes sure that only necessary pixel values are used from the additional camera view, and thus, reduces errors in the final HDR image. The resulting HDR images are compared with the quality metric HDR-VDP-2 and numerical results are given for the first time. For the Middlebury test images, an average gain of 52 points on a 0-100 mean opinion score is achieved in comparison to temporal exposure bracketing with camera motion. Finally, HDR video results are provided.     

High dynamic range swept time delay crosscorrelator

Analysis and theoretical results of a novel high dynamic range swept time delay crosscorrelator are presented. It is shown that, subject to the form of the post-multiplier filter employed, code self-noise is negligible and the dynamic range of the system is independent of the code length     

A wide dynamic range CMOS image sensor with pulse-frequency-modulation and in-pixel amplification

This paper briefly examines the pros and cons of CMOS pulse-frequency-modulation (PFM) digital pixel sensors. A pulse-frequency-modulation digital pixel sensor with in-pixel amplification is proposed to improve the resolution of the pixel sensor at low illumination. The proposed PFM digital pixel sensor offers the characteristics of a reduced integration time when the level of illumination is low with the fill factor comparable to that of PFM digital pixel sensors without in-pixel amplification. The proposed digital image sensor has been designed in TSMC- 1.8 V CMOS technology and validated using Spectre from Cadence Design Systems with BSIM3V3 device models. Simulation results demonstrate that the dynamic range of the proposed PFM digital pixel sensor with in-pixel amplification is 20 dB larger as compared with that of PFM digital pixel sensors without in-pixel amplification. The increased dynamic range is obtained in the low illumination condition where PFM digital pixel sensors without in-pixel amplification cease the operation due to the low photo current.     

A linear and wide dynamic range transimpedance amplifier with adaptive gain control technique

A linear and wide dynamic range transimpedance amplifier (TIA) for the pulsed time-of-flight imaging LADAR application has been designed and simulated in a 0.18 μm 3.3 V CMOS technology. Specific design techniques, including adaptive gain control technique to widen linear dynamic range, pseudo-differential structure of the front end to decrease the common-mode noise and noise minimization to improve SNR, have been proposed to achieve challenging designs goals with linear dynamic range of 5000:1, high transimpedance gain of 89 dB Ω, bandwidth up to 150 MHz, equivalent input-referred noise current less than 8 \({\text{pA}}/\sqrt {\text{Hz}}\), in 2 pF photodiode parasitic capacitance. The proposed TIA consumes 165 mW with 3.3 V power supply.     

基于图像绘制技术的红外场景模拟

红外场景模拟可为目标识别、跟踪提供必要的图像样本,对算法的训练、评估和可靠性检验具有十分重要的意义,基于建模的红外模拟方法不一定反映场景的客观情况,并且,计算量大、耗时,难于模拟出有真实感的红外图像。基于图像绘制技术,提出无需建模的基于图像的绘制方法来模拟红外场景图像,根据红外图像的特点,给出了计算基本矩阵的非线性迭代算法和基于特征约束的动态规划立体匹配算法。由于参考图集是实际图像,因此,模拟图像更符合景物的真实情况,并且,该方法无需很复杂的建模过程,利于实时模拟。实验结果表明,该方法可有效地模拟出真实感的红外图像。     

High spurious free dynamic range fibre link using a semiconductorelectroabsorption modulator

A 1.32 μm suboctave analogue fibre optic link with a measured spurious free dynamic range of 123 dBHz^4/5 has been demonstrated at an average detector photocurrent of 0.25 mA. This link employs a packaged InGaAsP electroabsorption waveguide modulator biased to suppress the third-order intermodulation distortion     

自适应统计范围调整的红外图像灰度信息统计算法

长波红外焦平面探测器以太空为背景成像后,图像灰度信息的统计量易受探测器固定坏元和随机坏元的影响,为解决此问题提出了一种自适应统计范围调整的红外图像灰度信息统计算法。其基本思想是在统计灰度信息时自适应设置一定的统计范围,尽可能排除坏元对统计灰度信息的影响。算法中建立线性模型描述当前帧统计得到的灰度信息与下一帧统计范围之间的关系,以统计均值的均方误差最小为准则调整线性模型参数。仿真实验表明,该算法能够追踪红外图像的背景渐变并自适应调整下一帧统计范围,克服了长波红外探测器中坏元对于统计过程的影响,为后续的处理提供准确的灰度信息。此外,该算法以一种序贯递推的方式执行,适合在对实时性要求较高的系统中实现。     

针对距离向处理的SAR自适应成像算法

在研究传统SAR成像处理过程的基础上,将自聚焦的概念加以拓广,提出了一种自适应成像算法.该算法摒弃了传统自聚焦算法对距离徙动已被完全纠正的假设,将自适应处理的时机前移到距离徙动校正阶段,通过修正若干系统参数使得距离徙动被完美地校正,这些被修正的参数将被应用到后续的处理过程中.该算法具有比传统自聚焦算法更好的成像精度及效果,令输出图像具有更好的相位保持特性.     

High dynamic range InP HBT delta-sigma analog-to-digital converters

To date, the development of multifunction multicarrier digital receivers for cellular base station and military communications applications has been limited by the demanding dynamic range requirements for the analog-to-digital converter (ADC). The use of oversampling delta-sigma modulators provides a promising approach to overcoming the dynamic range barriers Nyquist-rate converters face in the same applications. This paper discusses issues involved in the design of high-speed high dynamic range wide-band delta-sigma ADCs for such communications applications. Test results of prototype designs are also presented. The delta-sigma modulators described in this paper operate at sampling frequencies ranging from 1 to 2.5 GHz with center frequencies ranging from dc to 100 MHz, providing between 74 and 84.2 dB signal-to-noise ratio (12 and 13.7 bits) for bandwidths of 25 and 12.5 MHz, respectively. The loop filters are continuous-time low-pass and bandpass implementations of order 6 and 10, and were fabricated in an InP heterojunction bipolar (HBT) technology. A typical tenth-order design consumes 6 W of power and occupies a die area of 23.5 mm/sup 2/.     

High dynamic range 60 MHz powerline front-end IC

Presented for the first time, is a novel broadband powerline front-end realised in 0.25 mum SiGe BiCMOS with superior performance. The frequency range of the transmitter (TX) and the direct conversion receiver (RX) exceeds 60 MHz with a very wide dynamic range up to 99.5 dB for the lowest channel bandwidth. The integrated IF filter is tunable from 1 up to 8 MHz. The measured input-referred noise of the TX with low third intermodulation distortion (IMD3) is -140 and 144.5 dBm/Hz for the RX.     

High frequency/high dynamic range CMOS VGA

A novel CMOS variable gain amplifier (VGA) with high frequency and high dynamic range is proposed. The VGA has a controllable gain range of -50 dB-+50 dB which can be controlled by adjusting the external voltage as well as an enhanced operating frequency range up to 200 MHz. It is fabricated using 0.35 μm CMOS technology and has a core area of 580×660 μm