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1.
    
Abstract— A 1‐D LED‐backlight‐scanning technique and a 2‐D local‐dimming technique for large LCD TVs are presented. These techniques not only reduce the motion‐blur artifacts by means of impulse representation of images in video, but also increase the static contrast ratio by means of local dimming in the image(s). Both techniques exploit a unique feature of an LED backlight in large LCD TVs in which the whole panel is divided into a pre‐defined number of regions such that the luminance in each region is independently controllable. The proposed techniques are implemented in a Xilinx FPGA and demonstrated on a Samsung 40‐in. LCD TV. Measurement results show that the proposed techniques significantly reduce the motion‐blur artifacts, enhance the static contrast ratio by about 3×, and reduce the power consumption by 10% on average.  相似文献   

2.
    
Abstract— The contrast and power consumption of today's liquid‐crystal displays (LCDs) can be improved substantially by introducing (local) dimming backlights. In fact, infinite dynamic contrast and power savings of well over 50% have been claimed for such displays. Because these claims are generally made for very specific backlight designs and image content, the contrast gain and power savings are quantified as a function of the number of backlight segments for a large variety of image content.  相似文献   

3.
    
With the emergence of high‐dynamic range (HDR) image and video, displaying an HDR image or video on a standard dynamic range displays with natural visual effect, clear details on local areas, and high‐contrast ratio has become an important issue. To achieve HDR, local‐dimming technique has been commonly practiced. In this paper, we investigate the problem of local dimming for LED‐backlight LC display to provide algorithm support for developing HDR displays. A novel local‐dimming algorithm is proposed to improve the contrast ratio, enhance the visual quality, and reduce the power consumption of the LCDs. The proposed algorithm mainly consists of two parts. The first part is a backlight luminance extraction method based on dynamic threshold and the maximum grayscale of an image block to improve the contrast ratio and reduce the power consumption. In the second one, a pixel compensation method based on logarithmic function is used to improve the visual quality and contrast ratio. At the same time, in order to better smooth the backlight diffusion at the edges of the backlight luminance signal to enhance the accuracy of the pixel compensation, we draw on the idea of BMA and improve it to establish the backlight diffusion model with different low‐pass‐filter templates for different types of blocks. Simulation and measured results show that the proposed algorithm outperforms the competing ones in contrast ratio, visual quality, and power‐saving ratio.  相似文献   

4.
    
Conventional displays use at least three primaries for full‐color image reproduction. In this contribution, the reproduction of color images using an LCD system with two local dynamic primaries, based on a segmented backlight, will be discussed. The two primaries are chosen to minimize color error by means of total least squares. Simulation results indicate quite good color reproduction for a large set of video data even with a limited number of backlight segments. A statistical analysis of this video content shows that excellent color reproduction (?u′v′ < 0.020 for more than 99.0% of the pixels per frame) can be achieved for 74.2% of the frames using 9216 backlight segments.  相似文献   

5.
    
We evaluated the perceived image quality of High Dynamic Range (HDR) content rendered using different types of local dimming and organic light‐emitting diode (OLED) displays. Using an OLED display that is capable of achieving high contrast at a pixel level, we emulated local dimming displays to evaluate their image quality. In a set of subjective experiments, observers compared HDR images and videos rendered with different local dimming densities and native panel contrast. There was a strong effect of panel contrast on perceived quality and also a strong trend toward preference for a larger number of dimming zones. We also evaluated the panel contrast and number of local dimming zones necessary to achieve image quality comparable with OLED. The findings of these experiments demonstrated that the use of a high‐contrast panel remains of critical importance. Also, the preference for panel rendering mode remains robust to normal levels of indoor ambient light.  相似文献   

6.
    
This paper presents a rapid local backlight dimming method for interlaced video to improve the efficiency of displaying interlaced video. In the proposed method, we combine the line average deinterlacing algorithm with the local backlight dimming algorithm. In order to reduce the computational complexity and the backlight power consumption, three novel methods are proposed. The first is to add the sparse method to process the deinterlaced image. Second, the improved dynamic threshold method is used to calculate the dimming factor. And third, the odd field and even field of the same frame use the same backlight brightness to do backlight dimming. The simulation results show that the proposed method can reduce the computational complexity and power consumption, and the experiment results verify that the method can provide high display effect.  相似文献   

7.
    
Abstract— Novel LED backlight driving technology with a fully embedded LED driver IC is presented. This driving system and IC feature a high speed reduced swing differential signaling (RSDS) interface, an independent PWM controller with high‐resolution programming, and embedded scan logic. To attain high efficiency from the boost converter, highly advanced dynamic headroom control technology has been implemented onto the IC. The embedded current boosting function showed almost no brightness reduction when operated in scanning mode. The scanning function of the system improved motion blur values 26–44% compared to that of a non‐scanning LCD panel.  相似文献   

8.
    
Abstract— In conventional LCDs, the backlight is set to maximum luminance regardless of the image. For dark scenes, this approach causes light leakage and power waste. Especially, light leakage in dark scenes degrades the contrast ratio of LCDs; to circumvent this problem, local‐dimming systems have been proposed. In these systems, the LED backlight is divided into several local blocks and the backlight luminance of each local block is controlled individually, and pixel values are adjusted simultaneously according to the luminance profile of the dimmed backlight. In this paper, a method of determining the LED backlight luminance of each local block depending on the image is proposed; this method significantly improves the image quality of LCDs. First, we introduce methods of quantifying light‐leakage at dark gray levels and clipping at bright gray levels. Then, the proposed method to determine the dimming duty, which controls the LED backlight luminance by compromising between these two measures, was derived. The proposed algorithm preserves the original image with little clipping distortion and effectively reduces light leakage.  相似文献   

9.
    
Abstract— Because TV applications require proper motion portrayal, overdrive and impulse driving are both required. Advanced lamp control enables Scanning Backlight Technology to drive the LCD panel with a pulsed exposure. Adaptive Dual‐Pulse Technology can be applied to eliminate the induced image flicker. Light leaking through LCD panels driven to black can be described as a poor black level, limiting the contrast ratio. Adaptive Dimming Technology can be applied to dim the backlight, while maintaining image quality and saving power. The limited transmittance of LCD panels can be described as weak brightness. The transmission of the LCD panel should be maximized and Adaptive Boosting Technology can be used to boost the backlight (>100%). When combining these technologies, motion portrayal is enhanced, local brightness may double, and the contrast may be increased up to a factor of 20, still saving power.  相似文献   

10.
    
Abstract— Backlight dimming is a dominant method for power reduction in LCDs. Image processing with a simple boost and clip can compensate for such dimming‐restoring image brightness. We propose a low complexity approach which replaces hard clipping with smooth roll‐off to reduce clipping artifacts. An additional high‐quality approach uses a two‐channel spatial‐frequency decomposition to preserve highlight detail attenuated by the roll‐off. Image quality is improved and power savings can be increased by more‐aggressive backlight dimming.  相似文献   

11.
    
Abstract— Field‐sequential color (FSC) is a potential technique for low‐power liquid‐crystal displays (LCDs). However, it still experiences a serious visual artifact, color break‐up (CBU), which degrades image quality. Consequently, the “Stencil Field‐Sequential‐Color (Stencil‐FSC)” method, which applies local color‐backlight‐dimming technology at a 240‐Hz field rate to FSC‐LCDs, is proposed. Using the Stencil‐FSC method not only suppressed CBU efficiently but also enhanced the image contrast ratio by using low average power consumption. After backlight signal optimization, the Stencil‐FSC method was demonstrated on a 32‐in. FSC‐LCD and effectively suppressed the CBU, which resulted in more than a 27,000:1 dynamic contrast ratio and less than 40‐W average power consumption.  相似文献   

12.
    
Abstract— The LED‐array backlight technique dramatically enhances the dynamic range of an LCD and hence extends its ability to present images with high reality. This is achieved by modulating LEDs individually, thus providing an area‐adaptive backlight for the display. The spatial overlap of light from the LED (crosstalk) occurs due to the diffusion screen placed between the backlight and LCD layer. However, the crosstalk is not only a blessing for supplying high brightness but is also a curse for causing potential artifacts, making the derivation of an LED driving signal a challenging task. This paper formulates the problem into two mathematical models: an iterative de‐convolution approach and a linear optimization approach. Algorithms for solving these two models are provided. The first approach provides instantaneous and satisfactory results except for high‐intensity highlights in the image. The linear optimization method conquers this drawback, but requires much more computation, possibly requiring preprocessing of the target, and also introduces undesired artifacts. These two approaches are extensively evaluated by building an image database composed of 161 high‐dynamic‐range images.  相似文献   

13.
    
Abstract— The pixel brightness of an LCD panel perceived by a user is the product of the backlight brightness and the panel transmittance. In conventional LCD panels, the backlight brightness is constant and always at peak luminance. This design suffers from light leakage and power waste problems at dark scenes. This paper presents a new LCD system, which uses locally pixel‐compensated backlight dimming (PCBD). The proposed method combines backlight control and pixel processing for reducing light leakage and power consumption while keeping the image at the original brightness. Backlight luminance is dimmed locally in the dark‐image region, and pixel values are compensated synchronously according to the luminance profile of dimmed backlight. By reducing the light leakage, a static contrast of over 20,000:1 has been achieved on a large‐sized LCD panel with the proposed PCBD method. No obvious artifacts have been noticed as well. The power consumption of the panel can also be greatly reduced, depending on various video content. The PCBD method could be widely used for developing state‐of‐the‐art LCD panels with LED backlights.  相似文献   

14.
为了提高显著图的精确度,能够准确地提取显著目标,提出了结合局部对比和全局稀有度的显著性检测算法.该方法通过两个方面来衡量显著性:局部对比和全局稀有度.采用多尺度高斯差分模拟“中央周边差”计算中心点与其周围点的各特征之间的差异来描述局部对比,采用多尺度高斯卷积图像的特征及特征方差的概率计算全局稀有度,将局部对比和全局稀有度融合和归一化得到最终综合显著图.实验结果表明,该方法能较好地检测图像中的显著区域,在突出图像中不同物体边缘的同时,也能突出图像中同质区域的显著性,说明了结合局部和全局的算法能够得到更好的显著图.  相似文献   

15.
    
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16.
在大规模分布式存储系统中,元数据高性能服务和扩展性已成为一个重要的研究热点.在元数据服务器(metadata server,MDS)中,将元数据分解为目录对象和文件对象.目录对象为定位性元数据,提供文件所在位置和访问控制;文件对象为描述性元数据,描述文件的数据特性.每个MDS负责所有目录对象和自身的文件对象,同时,以目录对象ID和文件名为关键字的Hash值作为局部元数据查找表的索引,通过Bloom Filter算法将每个MDS的局部元数据查找表压缩成一个摘要,这样既可利用MDS中Cache,提高Cache的命中率,减少磁盘I/O次数,动态扩展MDS,又能够实现快速的元数据查找.  相似文献   

17.
现有的基于背景先验的显著性算法模型中存在先验区域选取不合理的问题,导致计算出的前景区域不准确,影响最终结果。针对该问题提出了基于对比度优化流形排序的显著目标检测算法。利用图像边界信息找出背景先验,设计出采用显著期望、局部对比度以及全局对比度三个指标来衡量先验质量的算法,并根据先验质量设计带权加法,代替简单乘法融合显著先验,从而使显著先验更加准确。从先验中提取显著区域时,更改了选取阈值的策略,更合理地选取出前景区域,再利用流形排序得到显著性图,从而使显著性检测结果更加准确。实验结果表明,与同类算法相比,所提算法突出显著区域,减少噪声,更符合人类视觉感知,并在处理时间上领先于深度学习方法。  相似文献   

18.
潘涛  徐为民 《计算机测量与控制》2015,23(7):2263-2265, 2269
桥吊摆角的准确测量是实现吊车防摇控制的前提条件;文中将视觉识别技术引入到吊车防摆控制中来,提出了基于局部梯度变化和标准差的图像自适应增强处理算法,解决了不同背光条件下吊绳摆动位置信息获取问题,有效地实现了桥吊负载摆绳图像特征的提取;同时,采用两次下采样和梯度法相结合的圆心的识别算法,解决了圆检测的实时性问题,从而成功识别出目标及其所在的空间位置,并用几何方法准确地测量出负载钢丝绳的摆角;最后,实验结果证实了该方法的有效性。  相似文献   

19.
    
Abstract— A high‐performance high‐efficiency LED‐backlight driving system for liquid‐crystal‐display panels is presented. The proposed LED‐backlight driving system is composed of a high‐efficiency DC‐DC converter capable of operating over a universal AC input voltage (75–265 V) and a high‐performance LED‐backlight sector‐dimming controller. The high efficiency of the system is achieved by using an asymmetrical half‐bridge DC‐DC converter that utilizes a new voltage‐driven synchronous rectifier and an LED‐backlight sector‐dimming controller. This controller regulates current using lossless power semiconductor switches (MOSFETs). The power semiconductor switches of the proposed DC‐DC converter, including the synchronous rectifier switch, operate with zero voltage, achieving high efficiency and low switch voltage stress using the asymmetrical‐PWM and synchronous rectifier techniques. To achieve high performance, the proposed driving system performs the sector dimming and the current regulation using low‐cost microcontrollers and MOSFET switching, resulting in high contrast and brightness. A100‐W laboratory prototype was built and tested. The experimental results verify the feasibility of the proposed system.  相似文献   

20.
    
We review the emerging mini/micro–light‐emitting diode (LED) displays featuring high dynamic range and good sunlight readability. For mini‐LED backlit liquid crystal displays (LCDs), we quantitatively evaluate how the device contrast ratio, local dimming zone number, and local light profile affect the image quality. For the emissive mini/micro‐LED displays, the challenges of ambient contrast ratio and size‐dependent power efficiency are analyzed. Two figure‐of‐merits are proposed for optimizing the optical and electrical performances of mini/micro‐LED displays.  相似文献   

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