高图像配准精度的非相干数字全息彩色成像

菲涅耳非相干相关全息是一种能记录非相干物体全息图的新型技术,在生物医学成像和三维遥感领域具有重要应用前景。针对高光谱成像过程中图像融合配准困难的问题,文中利用空间光调制器的可编程特性,设计并制作了波长分别为492、562、672 nm的三组焦距恒定的双透镜相位掩模,依次调用三种波长的掩模并记录对应波长下物体的全息图。由于三色记录光经对应波长掩模调制后在CCD表面汇聚的光斑位置及尺寸均相同,因此,全息图重建后获得的重建图像具有相同的横向放大率,可提高图像融合时的配准精度,免去繁杂的光谱图像空间配准算法,真正实现了全息彩色成像的高精度配准和实时融合。采用该系统记录骰子的全息图,经数值重建及色彩融合后得到了颜色重建性较好的彩色三维像。     

DSP utilization in digital color printing

This article discusses the utilization of DSP techniques to digital printing systems, particularly in transforming multidimensional signals from electronic to hardcopy formats by utilizing digital printing solutions and controlling the "marking" engine that is at the heart of the electrophotographic system. Researchers and DSP practitioners are urged to share their vision on the novel use of signal processing algorithms to analyze, manipulate, and solve problems related to high-end digital printing.     

Digital color imaging

This paper surveys current technology and research in the area of digital color imaging. In order to establish the background and lay down terminology, fundamental concepts of color perception and measurement are first presented using vector-space notation and terminology. Present-day color recording and reproduction systems are reviewed along with the common mathematical models used for representing these devices. Algorithms for processing color images for display and communication are surveyed, and a forecast of research trends is attempted. An extensive bibliography is provided.     

彩色数字照相机的设计

提出了一种基于ＣＭＯＳ图像传感器和通用数字信号处理器的低价格、高质量彩色数字照相机的设计方案。介绍了系统的软硬件结构,详细描述了用数字图像处理的方法实现自动聚焦控制、自动曝光控制、ＲＧＢ色彩插值和快速离散余弦变换等关键技术。其设计性能优良,能获取分辨率为１ ０２４×７６８像素的高质量彩色数字照片。     

数字视频颜色校正的重要性

根据不同要求,使用应用软件对影像进行颜色校正,在后期制作中十分重要。从颜色属性、拍摄环境和摄像机造成的色差、颜色对视觉的影响和颜色校正等几个方面,叙述了颜色校正的重要性。     

Vector filtering for color imaging

Vector processing operations use essential spectral and spatial information to remove noise and localize microarray spots. The proposed fully automated vector technique can be easily implemented in either hardware or software; and incorporated in any existing microarray image analysis and gene expression tool.     

电子航图的颜色校正技术研究

电子航图在飞行仿真领域有着重要应用,然而由于局部纸质航图尺寸、来源及扫描设备等因素的影响,扫描得到的各个子航图颜色不一致,严重影响航图的整体效果.因此本文重点讨论了电子航图的颜色校正问题,利用相郊子航图间的重重叠域,采用线性映射变换的方法,在RGB、YIQ、YUV、HIS 4种颜色空间下对电子航图进行校正和比较.实验结...     

基于图像信息的彩色PDP动态子场编码优化方法

为改善"累积"发光驱动方法显示静态图像时的灰度级轮廓,提出了一种基于有效灰度级均匀分割采样的动态子场编码(DSC)算法。首先对输入图像中的孤立灰度区间进行灰度采样,然后对剩余灰度级均匀分割,选择各灰度区间概率密度较大的灰度级作为采样灰度级,相邻采样灰度级之差即为子场编码权值,从而使采样灰度级均匀分布在输入图像的有效灰度区间,并使采样灰度级和子场编码权值随图像变化。仿真和实验结果表明,该算法不仅能真实再现大面积的背景,而且使图像细节信息尽可能保留,显著减小了静态图像的轮廓。     

熊猫目标直指数字高端彩电第一阵营

在熊猫电子集团近期举办的一次新品展示会上,熊猫家电产业集团总经理董志明正式宣布,熊猫将全面参与数字高端产品的竞争,目标直指数字高端彩电第一阵营.     

基于彩色数字图像的车牌识别研究

车牌识别是图像识别技术在智能交通领域应用的重要研究之一,是实现交通管理智能化的重要环节。我国交通管理部门对汽车牌照的样式制定了严格的规范,这些规范将为车牌自动识别技术的实现提供重要的技术依据。车牌识别研究充分利用这些规范进行设计,采用彩色数字图像模式识别方法,针对彩色为24位,大小为640×480,以及蓝底白字车牌的图像进行识别研究,并具体描述图像车牌的预处理、车牌特征提取和车牌识别三个连续的过程。在Visual C++环境下实现对汽车牌照自动识别功能。实验结果表明,车牌识别自动技术识别效果可靠,具有很好的实用性。     

Color fringe removal in narrow color regions of digital images

Color fringe is an artifact that should be removed in a color digital image. This paper proposes a detection method of color fringe in narrow color regions. Near-saturation region (NSR) information as well as gradient magnitudes and directions of RGB color components are used to detect transition regions, in which color fringe occurs. Four gradient directions are used in order to improve the performance of color fringe detection. NSR is used to prevent excessive detection of possible color fringe regions. Then, the detected color fringe is removed using the color difference values. Experimental results show the effectiveness of the proposed color fringe removal method.     

Automatic detection of red lesions in digital color fundus photographs

The robust detection of red lesions in digital color fundus photographs is a critical step in the development of automated screening systems for diabetic retinopathy. In this paper, a novel red lesion detection method is presented based on a hybrid approach, combining prior works by Spencer et al. (1996) and Frame et al. (1998) with two important new contributions. The first contribution is a new red lesion candidate detection system based on pixel classification. Using this technique, vasculature and red lesions are separated from the background of the image. After removal of the connected vasculature the remaining objects are considered possible red lesions. Second, an extensive number of new features are added to those proposed by Spencer-Frame. The detected candidate objects are classified using all features and a k-nearest neighbor classifier. An extensive evaluation was performed on a test set composed of images representative of those normally found in a screening set. When determining whether an image contains red lesions the system achieves a sensitivity of 100% at a specificity of 87%. The method is compared with several different automatic systems and is shown to outperform them all. Performance is close to that of a human expert examining the images for the presence of red lesions.     

An NMOS dual-mode digital low-pass filter for color TV

A low-pass filter for separation of the luminance and chroma spectra is dealt with. The function of the filter and the implementation of the filter on a chip are briefly described and the circuit design is discussed in some detail. The chip, which runs at frequencies up to 40 MHz, has been designed with two-phase race-compensated MOS logic in a 4 /spl mu/m E/D NMOS technology with implanted undercrossings.     

遥感数字图像无损彩色合成研究

针对目前遥感数字图像彩色合成中存在的色调失真、异常亮点过多、丢失图像细节信息等问题,对其采用了无损平移双向拉伸彩色合成增强方法进行图像彩色合成。实验表明该方法做到了有效像素亮度值的无损增强,保持了遥感数字图像信息的完整性,并且图像的色调适中,目视判读效果良好;该方法适用于卫星遥感数字图像的彩色合成增强处理,为遥感数字图像的信息提取和处理奠定了良好的基础,并且有很高的实际应用价值。     

基于彩色数字全息的透镜焦距检测

为了实现对凹凸透镜焦距的精准测量,采用彩色数字全息方法进行理论分析和实验验证,取得了与标称值相差1%的数据结果。结果表明,采用数字全息干涉测量方法是可靠的,可以获得与用透镜标称值重构相同的效果。该研究对数字全息波前的重建有帮助。     

Device optimization for digital subthreshold logic operation

Digital circuits operated in the subthreshold region (supply voltage less than the transistor threshold voltage) can have orders of magnitude power advantage over standard CMOS circuits for applications requiring ultralow power and medium frequency of operation. Although the implication of technology scaling on subthreshold operation is not obvious (since an obsolete technology node can deliver the same performance as a scaled technology in subthreshold), it has been shown that technology scaling helps to reduce the supply-voltage and, hence, the power consumption at iso-performance. It is possible to implement subthreshold logic circuits using the standard transistors that are designed primarily for ultra high performance super-threshold logic design. However, an Si MOSFET so optimized for performance in the super-threshold regime is not the best device to use in the subthreshold domain. We propose device designs apt for subthreshold operation. Results show that the optimized device improves the delay and power delay product (PDP) of an inverter chain by 44% and 51%, respectively, over the normal super-threshold device operated in the subthreshold region.     

傅立叶计算全息数字水印在彩色图像印刷防伪中的应用

设计了一种针对彩色图像打印-扫描过程的基于傅立叶计算全息技术的数字水印系统.在该系统中我们首次提出将傅立叶计算全息数字水印技术应用于彩色图像印刷防伪,并为之设计了相应的提取程序.该系统与目前其他的针对打印-扫描过程的数字水印系统相比,具有抗剪切、盲检测、水印信息量大等特点.在彩色图像印刷防伪方面具有明显的应用前景.     

Automated measurement of the arteriolar-to-venular width ratio in digital color fundus photographs

A decreased ratio of the width of retinal arteries to veins [arteriolar-to-venular diameter ratio (AVR)], is well established as predictive of cerebral atrophy, stroke and other cardiovascular events in adults. Tortuous and dilated arteries and veins, as well as decreased AVR are also markers for plus disease in retinopathy of prematurity. This work presents an automated method to estimate the AVR in retinal color images by detecting the location of the optic disc, determining an appropriate region of interest (ROI), classifying vessels as arteries or veins, estimating vessel widths, and calculating the AVR. After vessel segmentation and vessel width determination, the optic disc is located and the system eliminates all vessels outside the AVR measurement ROI. A skeletonization operation is applied to the remaining vessels after which vessel crossings and bifurcation points are removed, leaving a set of vessel segments consisting of only vessel centerline pixels. Features are extracted from each centerline pixel in order to assign these a soft label indicating the likelihood that the pixel is part of a vein. As all centerline pixels in a connected vessel segment should be the same type, the median soft label is assigned to each centerline pixel in the segment. Next, artery vein pairs are matched using an iterative algorithm, and the widths of the vessels are used to calculate the AVR. We trained and tested the algorithm on a set of 65 high resolution digital color fundus photographs using a reference standard that indicates for each major vessel in the image whether it is an artery or vein. We compared the AVR values produced by our system with those determined by a semi-automated reference system. We obtained a mean unsigned error of 0.06 (SD 0.04) in 40 images with a mean AVR of 0.67. A second observer using the semi-automated system obtained the same mean unsigned error of 0.06 (SD 0.05) on the set of images with a mean AVR of 0.66. The testing data and reference standard used in this study has been made publicly available.     

Noise reduction using multiscale bilateral decomposition for digital color images

In this paper, we propose a noise reduction algorithm for digital color images using a nonlinear image decomposition approach. Most existing noise reduction methods do not adequately consider spatial correlation of color noise in digital color images. Color noise components in color images captured by digital cameras are observed as irregular grains with various sizes and shapes, which are spatially randomly distributed. We use a modified multiscale bilateral decomposition to effectively separate signal and mixed-type noise components, in which a noisy input image is decomposed into a base layer and several detail layers. A base layer contains strong edges, and most of noise components are contained in detail layers. Noise components in detail layers are reduced by an adaptive thresholding function. We obtain a denoised image by combining a base layer and noise-reduced detail layers. Experimental results show the effectiveness of the proposed algorithm, in terms of both the peak signal-to-noise ratio and visual quality.