背光图像的检测与校正

针对传统背光图像检测低准确率问题,提出一种新的背光图像检测和校正算法。通过分析图像在不同Gamma变换下前景细节数目的变化规律来判断输入图像是否存在背光。对背光图像的前景、背景子图像进行多尺寸Retinex图像算法,然后与原图进行融合。根据实验可知,提出的背光图像检测算法相对于传统的亮度直方图分析方法以及YCbCr直方图分析方法具有更高准确率;提出的背光校正算法相对于AHMHE背光补偿算法和多尺度Retinex算法具有较高信息熵、清晰度和对比度。     

Human visual sensitivity based optimal local backlight dimming methodologies under different viewing conditions

An adaptive local backlight dimming algorithm is proposed considering human visual sensitivities under various viewing conditions. Local dimming amount is maximized based on contrast sensitivity function and local image characteristics to minimize perceived luminance and contrast losses maintaining image qualities. Average luminance, contrast and spatial frequency are evaluated as local image characteristics. As dimming based on local characteristics has blocking artifacts, a compensation method using edge luminance difference is proposed considering human responses. The proposed algorithms reduce backlight power consumption by 39.69% on average, with an average SSIM of 0.995. It can be increased by 5.66% with varying viewing conditions, resulting in a 45.35% power consumption reduction on average. The outperformances of the proposed algorithm in power consumption reduction and maintaining image quality are verified with various image quality metrics compared to recent dimming algorithms.     

High‐performance local‐dimming algorithm based on image characteristic and logarithmic function

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.     

离焦图像多视角模糊特征自动补偿仿真研究

传统离焦图像多视角模糊特征自动补偿方法存在着图像信息丢失率大、图像补偿完整度低的弊端,为了解决上述问题,提出离焦图像多视角模糊特征自动补偿方法研究。为了得到更好的模糊特征补偿效果,对离焦图像形成过程进行分析,以此为基础,对离焦图像多视角模糊模型进行构建,以构建的离焦图像多视角模糊模型为工具,采用聚类算法对离焦图像模糊特征进行相应的提取,以提取的离焦图像多视角模糊特征为基础,采用补偿算法对离焦图像多视角模糊特征进行处理,实现了离焦图像多视角模糊特征的自动补偿。通过仿真对比实验得到,与现有的三种离焦图像多视角模糊特征自动补偿方法相比较,提出的离焦图像多视角模糊特征自动补偿方法极大的降低了图像信息丢失率,提升了图像补偿完整度,充分说明提出的离焦图像多视角模糊特征自动补偿方法具备更好的补偿性能。     

运动估计与运动补偿在电子稳像中的应用

电子稳像系统的核心是运动估计和运动补偿。为了提供运动估计的精度和降低时间开销，达到实时应用的要求，该文提出了基于宏块的步进全局运动估计算法，获得图像序列的全局运动矢量；给出了一个新的应用于电子稳像系统中运动估计与运动补偿模块的运动估计、运动补偿原理框图；采用两步补偿算法完成对图像序列的运动补偿，得到稳定的图像序列输出。仿真结果表明，采用的方法是高效、可行的。     

一种能实现免脱帽人脸识别系统算法

针对人脸识别系统在人脸被遮挡情况下识别率低的问题,为进一步提升人脸在遮挡情况下的识别率,文章提出一种通过图像多方向梯度值,使用融合、补偿等方式产生可以对原图像进行特征描述的特征图像,通过对特征图进行一系列处理后实现人脸识别的算法;算法首先计算图像四方位的梯度值;其次对4个梯度值进行融合运算,产生合融梯度、差融梯度;再次以合融梯度、差融梯度作为补偿变量在原图像上进行适当系数的补偿,形成人脸图像特征图;然后对特征图依次进行直方图统计、主成分分析后,使用SVM分类器进行分类识别;使用Matlab2016试验仿真平台在ORL、CMU_PIE等多个人脸数据库上进行测试,分别取得100%、92.21%的准确率,结果表明推荐算法在人脸被遮挡情况下的识别率具有很好的表现。     

Adaptive height-modified histogram equalization and chroma correction in YCbCr color space for fast backlight image compensation

Automatic exposure controls in commercially available cameras often encounter difficulties in capturing scenes with backlight luminance which dominates the entire image. An Adaptive Height-Modified Histogram Equalization (AHMHE) algorithm is proposed as a compensation technique for backlight images. It simultaneously enhances contrast in both the dark and the bright areas without creating regions of degraded local contrast. Moreover AHMHE is an adaptive algorithm: thus it requires minimal user input, and its reduced computational requirement makes it suitable for real-time application. In addition to AHMHE, a chroma correction technique was applied to chroma components in the YCbCr color space to produce more vivid color images. A series of subjective and index evaluations were conducted to measure the resultant image quality improvements by the AHMHE and the chroma correction algorithms.     

IPS‐mode dynamic LCD‐TV realization with low black luminance and high contrast by adaptive dynamic image control technology

Abstract— In this paper, an active backlight control technology and a data‐processing algorithm has been developed to improve the image quality in IPS‐mode LCD TVs. The image‐blinking problem caused by repeatedly abrupt changes in the backlight luminance was solved by using algorithms [Fba (flexible‐boundary algorithm) and Cfa (cumulative feedback algorithm)] and an optimized number of backlight dimming steps based on human perception. In the IPS‐mode 42‐in. TFT‐LCD panel, the dynamic contrast ratio can be more than twice the typical level by means of a lower black luminance and a higher white luminance. Additionally, the power consumption and LCD temperature were lowered.     

改进非线性亮度提升模型的逆光图像恢复

针对因为拍照时光线不足或拍摄角度不佳而拍出逆光图像影响肉眼观察或计算机识别的问题,提出一种改进的非线性亮度提升模型的逆光图像恢复手段。已有的非线性亮度提升方法虽然能够提高逆光区域的亮度,但往往由于过度提升导致高亮度区域失真。在已有的图像亮度处理算法基础上,提出基于非线性亮度提升模型的自适应逆光图像恢复方法,采用对数函数的转换关系对图像亮度进行分段处理,其分段阈值由Otsu阈值分割决定,其转换函数中逆光区域的调节系数由逆光区像素面积比计算得到。仿真结果显示,新方法提升了图像质量且确保了整幅图片自然不失真,与利用对数函数转换关系,并在HSI空间模型下对图像亮度进行调节的方法相比,提升了处理性能。