Real-time digital image enhancement

A programmable system for enhancing monocular and stereographic images at video rates is presented. The system provides both automatic and interactive enhancement modes based on histogram modification and intensity mapping techniques. Experimental results which illustrate enhancement capabilities under a variety of scene types and conditions are described.     

Underwater image enhancement with image colorfulness measure

Due to the absorption and scattering effects of the water, underwater images tend to suffer from many severe problems, such as low contrast, grayed out colors and blurring content. To improve the visual quality of underwater images, we proposed a novel enhancement model, which is a trainable end-to-end neural model. Two parts constitute the overall model. The first one is a non-parameter layer for the preliminary color correction, then the second part is consisted of parametric layers for a self-adaptive refinement, namely the channel-wise linear shift. For better details, contrast and colorfulness, this enhancement network is jointly optimized by the pixel-level and characteristic-level training criteria. Through extensive experiments on natural underwater scenes, we show that the proposed method can get high quality enhancement results.     

Wavelet domain image resolution enhancement

A wavelet-domain image resolution enhancement algorithm which is based on the estimation of detail wavelet coefficients at high resolution scales is proposed. The method exploits wavelet coefficient correlation in a local neighbourhood sense and employs linear least-squares regression to estimate the unknown detail coefficients. Results show that the proposed method is considerably superior to conventional image interpolation techniques, both in objective and subjective terms, while it also compares favourably with competing methods operating in the wavelet domain.     

低信噪比图像的模糊增强算法

传统的机器视觉方法应用于低信噪比图像的目标增强,增强结果容易受噪声影响,鲁棒性较差.本文提出一种基于最大模糊熵的图象增强算法,对不同复杂背景下的图像具有增强函数强度自动可调和运算速度快的优点.其算法的实现关键是利用遗传算法自动搜寻满足最大熵条件的模糊增强函数的最佳带宽参数.进化过程中运用实数编码,在父代染色体构成的超平面内运用高斯交叉、变异算子创建后代,并采用欧式距离自适应调节交叉、变异概率.通过实验证明,该算法能够有效的增强复杂背景下的微弱目标信号.     

基于图像增强和复原的图像去雾方法研究

雾霭等天气下获得的图像存在对比度低、颜色退化、景物模糊等一系列图像退化的问题,直接影响了对图像信息的有效利用。因此,对雾天图像进行有效的去雾处理,有效改善降质图像的质量,具有一定的实际意义。分析讨论基于图像增强的多尺度Retinex算法和利用图像复原原理的基于暗原色先验理论的去雾算法,并对具有不同特点的单幅有雾图像进行去雾仿真。实验结果表明,不同理论基础的两种去雾算法各有特点,基于暗原色理论处理得到的图像去雾效果更显著,算法运行速度更快。     

Color image enhancement via chromaticity diffusion

A novel approach for color image denoising is proposed in this paper. The algorithm is based on separating the color data into chromaticity and brightness, and then processing each one of these components with partial differential equations or diffusion flows. In the proposed algorithm, each color pixel is considered as an n-dimensional vector. The vectors' direction, a unit vector, gives the chromaticity, while the magnitude represents the pixel brightness. The chromaticity is processed with a system of coupled diffusion equations adapted from the theory of harmonic maps in liquid crystals. This theory deals with the regularization of vectorial data, while satisfying the intrinsic unit norm constraint of directional data such as chromaticity. Both isotropic and anisotropic diffusion flows are presented for this n-dimensional chromaticity diffusion flow. The brightness is processed by a scalar median filter or any of the popular and well established anisotropic diffusion flows for scalar image enhancement. We present the underlying theory, a number of examples, and briefly compare with the current literature.     

医学图像增强系统设计

为了改善医学图像的视觉效果,提高图像的清晰度,使之更适合于机器的分析处理以及人的视觉特性,并突出病灶点,为病理学诊断和临床诊断提供可靠依据。设计了一个对医学图像十分具有针对性的图像增强系统。针对CT图像的电子噪声提出了基于修正维纳滤波的小波包去噪算法;针对B型超声图像的散斑噪声提出了基于脉冲耦合神经网络(PCNN)模型的小波自适应斑点噪声滤除算法;针对医学图像对比度低,边缘信息模糊等特点,提出了基于小波变换的医学图像增强算法。当噪声方差为0.01时,基于脉冲耦合神经网络(PCNN)模型的小波自适应斑点噪声滤除算法获得的PSNR比经Wiener滤波方法获得的PSNR高出9 dB。系统能快速找到噪声点进行定点去噪,能有效提高医学图像的对比度,增强边缘细节信息,突出病灶点的位置,从而达到较好的处理效果,为医疗工作者观察病症提供更加清晰准确的依据。     

基于Piecewise直方图均衡化的图像增强方法

提出了一种基于Piecewise直方图均衡化的图像增强方法,有机地结合了亮度拉伸和传统直方图均衡化的优点。通过定义直方图中相邻灰度级的距离,引入了一个基于直方图均值和标准偏差的Piecewise线性变换,探讨了图像过亮时Piecewise直方图均衡化参数的选取。实验表明,该方法的处理结果能有效避免现有的直方图均衡化方法中的"吞噬"问题和亮度饱和问题。在增强图像时不仅能保留细节,而且具有更加自然的视觉效果。     

基于偏振成像的红外图像增强

针对红外图像对比度低,细节纹理较弱的特点,利用物体偏振特性提出基于偏振成像的红外图像增强方法,即获取红外偏振度图像并与源光强图像融合。首先,分析了偏振成像理论,利用偏振成像技术获取偏振图像。其次,为了能够充分获取偏振度图中的信息,运用剪切波变换对图像进行多尺度分解。最后,采用区域特征匹配融合策略,得到增强图像。为测试方法的有效性,搭建实验装置,进行实拍图像实验。主观与客观评价结果均表明,增强后的图像较原图像具有更加丰富的图像细节与偏振目标信息,对目标识别与探测具有重要意义。     

Recent data on image enhancement programs

Some internal input-output differences between the CDC 6600 and 7600 computers are reviewed, along with the effect of those differences on programs for enhancing large images (1024 by 1024 matrix). Recent data from a program for the CDC 7600 are presented, showing a factor of 5 greater speed over a previously reported program.     

织物图像增强技术的研究

对具有不同特性的织物数字图像利用二维离散傅立叶变换进行图像增强和图像复原等操作,能有效地改善图像的 质量,突出所需要的细节,为织物密度的自动测量提供最佳质量的图像.研究了二维离散快速傅立叶变换算法,以及利用该 算法在频率域中进行图像增强和图像复原的新方法.实验结果分析表明,利用提出的方法可以较好地改善织物图像的质量.     

Transform-based image enhancement algorithms with performancemeasure

This paper presents a new class of the "frequency domain"-based signal/image enhancement algorithms including magnitude reduction, log-magnitude reduction, iterative magnitude and a log-reduction zonal magnitude technique. These algorithms are described and applied for detection and visualization of objects within an image. The new technique is based on the so-called sequency ordered orthogonal transforms, which include the well-known Fourier, Hartley, cosine, and Hadamard transforms, as well as new enhancement parametric operators. A wide range of image characteristics can be obtained from a single transform, by varying the parameters of the operators. We also introduce a quantifying method to measure signal/image enhancement called EME. This helps choose the best parameters and transform for each enhancement. A number of experimental results are presented to illustrate the performance of the proposed algorithms.     

一种指纹奇异点区域图像增强算法

指纹图像奇异点附近区域的增强一直是指纹图像增强的难点,针对Separable Gabor滤波会破坏指纹邻近奇异点区域的纹线结构,方向傅里叶滤波在一般区域修复指纹纹线效果不明显这一问题,本文融合两种算法的优势,提出一种新的滤波方法(FS-Gabor)。先对指纹图像进行预处理,得到指纹的方向、频率信息和掩膜信息。接着找出指纹图像的奇异点,并在奇异点附近标记出一定大小区域。最后根据像素点的位置采用不同的滤波方法。同时,本文提出了一种改进的指纹图像频率估计方法,扩大了指纹图像有效区域面积。实验结果表明,经本文方法滤波的指纹图像的EER(Equal Error Rate)比方向傅里叶滤波低26%,比Separable Gabor低49%。     

Digital contour enhancement of infrared image

The digital contour enhancement techniques of infrared image are discussed. Emphasis is laid the thermal spread compensation method. On the basis of describing the theory of the method, the model is suggested. The concrete project based on the model for realizing digital contour enhancement of the infrared thermal image is put forward, and some test results are shown.     

Global image enhancement using local information

After defining an indiscernibility relation and performing a region fusion process, regions are formed from the image. The histogram is constructed using the mean grey level of each region; a histogram equalisation process is applied to obtain the transformation function for enhancement. This new method, LIHE, demonstrates better results both visually and quantitatively.<>     

图像通信中一种低照度彩色图像增强算法

针对低照度彩色图像细节模糊、亮度不高等问题,提出一种新的彩色图像增强算法。首先引入新传递函数改进传统同态滤波,然后,在RGB色彩空间上,分别对R、G、B分量用改进的同态滤波和对比度受限自适应直方图均衡（CLAHE）进行增强。接着,转换到HSV色彩空间,用非线性函数对亮度进行光照补偿,对饱和度进行1.5倍拉伸。最后恢复图像色彩信息。实验结果表明,新算法在保持图像细节的同时能够增强图像对比度,使图像清晰度更高。     

运用小波图像融合技术增强痕迹偏振图像

针对单幅痕迹偏振图像存在的灰度反差微弱、痕迹特征残缺等缺陷,提出运用小波图像融合技术对多幅痕迹偏振图像进行融合处理,以增强痕迹图像视觉效果的策略。结合痕迹物证检验工作的需要,对低频子带图像采取基于区域窗口的梯度平方和较大法,而高频子带图像采取基于区域窗口的系数绝对值极大法,并将此方案应用于衣物上的轮胎痕迹偏振图像的增强处理。实验结果表明,经过融合处理后的轮胎痕迹偏振图像无论在主观视觉效果,还是在客观评价数据上都获得了期望的增强效果,满足痕迹物证司法鉴定的技术要求。     

Gamma变换与多尺度细节增强的红外图像增强北大核心CSCD

针对现有的红外图像增强方法存在欠增强、过增强以及微小细节不清晰等缺陷,提出了一种Gamma变换与多尺度细节增强的红外图像增强方法。该方法充分利用红外图像边缘细节的多尺度特性,用多尺度的引导滤波将红外图像分解为多尺度的细节层和基础层;对基础层进行自适应的Gamma变换,Gamma指数自适应于基础层图像亮区像素数与暗区像素数的比值,旨在适宜地调整红外图像的整体亮度,使得隐藏于暗区的图像信息得以正常显示;对多尺度的细节层分别进行四邻域的拉普拉斯增强,以提升多尺度细节信息的信号强度。实验数据证明,相对于部分最新的现有方法,本文方法具有更好的增强效果,增强图像的视觉感知效果更佳,客观的图像质量指标平均梯度和无参考图像质量指标均较高。     

Color retinal image enhancement using luminosity and quantile based contrast enhancement

Multidimensional Systems and Signal Processing - Retinal imaging is used to diagnose common eye diseases. But retinal images that suffer from image blurring, uneven illumination and low contrast...     

利用导向滤波的宽动态范围图像增强技术

随着现代CCD和CMOS相机阵列尺寸的增大,越来越多的像素被集成到焦平面阵列上。基于该项技术可以获取更高分辨率和更宽动态范围的图像,该图像包含了更多真实的细节信息。然而,在处理这种图像的时候,尽管图像具有宽动态范围,但是却无法显示图像的所有有用信息。一些技术已经被用于先进的相机以解决上述问题,但它们还是存在或多或少的缺点。因此,提出了一种新的宽动态范围图像增强算法。该算法使用导向图像滤波器对图像进行分割,然后同时处理被分割的基频层以及细节层。通过增强高频信号来突出细节层中图像的细节,同时使用策略处理基频层以控制灰度对比度。颜色饱和度可以通过两个层一起控制。通过细节层和基频层来增强原始宽动态范围图像,提高数字细节、灰度自适应以及颜色对比度。对算法进行了详细的分析。图像仿真示例显示该算法性能可靠。