一种基于HSV分量分层的彩色图像快速压缩方法

根据彩色图像的数据结构将图像转化为适应人类视觉系统的HSV模式分量,并排列组合成新的灰度图像,将该灰度图像实行粗细分层操作后分别按JPEG压缩标准进行压缩编码.实验表明,该算法得到的压缩图像在与JPEG同等质量的条件下,数据量要远小于JPEG压缩的数据量,操作简单快速,可实现彩色图像的高质量快速压缩和预览.     

一种分形彩色图像压缩编码方法

在分析彩色图像色彩三分量r,g,b的相关性和分形四叉树编码层次信息冗余性的基础上,提出了一种分形彩色图像压缩编码方法.它将图像的3个独立的颜色分量按某种方式组合成1个来搜索匹配块,从而将需要存储和搜索的3个颜色分量匹配块(SFC方法)减少为1个,并且对四叉树层次信息进行压缩.此外,采用不同的组合,得到了几个图像压缩比和解码质量相近的编码方法,其中使用亮度分量的方法比使用其他方法速度更快.实验结果表明,它优于SFC方法及标准JPEG方法,不失为一种好的分形彩色图像压缩方法.     

基于JPEG的图像无损分区压缩

为了适应图像的存储和传输,需要对图像进行压缩以减少数据量,因此,许多压缩技术和标准应运而生.利用JPEG压缩标准,根据图像的数据结构将图像进行了分区域操作,从而实现JPEG压缩模式下的无损压缩.实验结果表明,该算法得到的压缩图像在与JPEG同等质量的条件下,数据量要小于JPEG压缩的数据量.     

主成分分析用于图像压缩预处理的比较研究

JPEG是一种广泛应用的图像压缩和解压缩标准,其预处理采用简单的线性变换,将彩色图像从RGB转换到亮度/色度空间(YCbCr),达到了去除分量之间相关性的目的。为获取高压缩率,文章提出了以主成分变换进行彩色图像预处理的方法,该方法对每个图像单元进行变换,去除彩色分量之间的相关性。实验表明,其去相关性能优于JPEG的线性变换,并且在同压缩比下,其PSNR高于JPEG,图像质量优于JPEG。     

一种使用四叉树分割的分形信息隐藏算法

目前的正交分形信息隐藏算法在进行正交分形编码时都是等分割原始图像,这样无法自适应图像内容且耗时,并且在处理彩色图像时没能考虑分量之间的相关性以及拼贴误差,因此鲁棒性较差。提出一种采用四叉树分割的正交分形信息隐藏算法。该算法能够根据图像特征实现原始图像的四叉树分割,同时考虑彩色图像R、G、B三个分量的相关性,提取亮度分量进行分形编码,并利用拼贴误差特性,动态调整分型参数的修改量来嵌入秘密图像。实验及应用表明,该算法编码时间短、具有很好的透明性以及对JPEG压缩、加噪、滤波、几何形变等具有较好的鲁棒性。     

基于HVS和交叉掩蔽的彩色图像编码算法

以层树分集（SPIHT）编码方案为基础,结合人类视觉系统（HVS）模型和人类视觉对彩色图像分量亮度和色度的不同敏感性,提出了一种基于非对称编码和交叉掩蔽的小波域彩色图像压缩编码算法。该算法首先将原始图像从RGB空间转换到YCbCr空间,然后对YCbCr空间的各分量进行离散小波变换;之后根据人类视觉对彩色图像的亮度分量的敏感性,用交叉掩蔽模型对亮度分量的小波系数进行加权处理;与此同时,利用非对称编码和SPIHT编码思想完成图像的压缩。仿真实验结果表明,文中算法是一种高效的图像压缩编码方法,其压缩效果明显优于SPIHT编码方案。     

一种使用正交分形编码的彩色图像水印算法

传统的正交分形水印算法,很多情况下只是针对灰度宿主图像,且嵌入的水印多为随机序列或二值图像,实用性不强.当这些算法在处理彩色宿主图像时,通常采用的是将R,G,B三个分量单独处理的SFC方法,没能考虑到分量之间的相关性,因此算法的鲁棒性较弱.文提出一种在彩色图像中利用正交分形编码嵌入灰度水印的算法,该算法在对彩色宿主图像进行正交分形编码的基础上,考虑彩色图像R,G,B三个分量的相关性以及拼贴误差特性,通过变换函数以及修改分形编码参数来嵌入灰度水印.实验及应用表明,该算法隐蔽性强,并对剪切、涂抹、加噪以及JPEG压缩等具有较强的鲁棒性.     

基于RGB色彩空间的彩色图像混合编码

在RGB色彩空间,利用彩色图像3个色彩分量之间存在的密切的相关性,建立它们之间的多项式相关函数.选择其中一个色彩分量用JPEG2000进行编码,依据该色彩分量与另两个色彩分量的差值分布均匀程度,用四又树算法将图像分割成若干个不重叠的子块,用多项式相关函数计算出每个子块色彩分量之间的相关系数,由此对另两个色彩分量的编码就转变成对相关系数的编码.解码则是通过JPEG2000的逆变换得到一个重构的色彩分量,再由这个重构的色彩分量和重构的相关系数解得另两个色彩分量.实验结果表明,该方法不仅编解码速度快,而且信噪比、压缩比及视觉效果明显优于JPEG2000等算法的编码结果.     

基于扩频调制和视觉掩蔽的彩色图像盲水印算法

为了更好地实现彩色图像的版权保护,首先,从理论上说明了应该选择彩色图像绿色分量嵌入水印,然后提出了一种新的适应彩色图像的盲水印算法。该算法先对宿主图像的绿色分量以8×8pixels分块进行DCT变换;然后将二值水印图像用两个互不相关的伪随机序列进行扩频调制;最后为了最大限度地增强水印强度,且不影响透明性,通过引入人眼视觉掩蔽因子,将调制好的水印根据视觉掩蔽因子大小,不同强度地嵌入到DCT变换域的中频子带系数上。该算法是通过比较两个伪随机序列和水印化图像的相关性大小来提取水印,不需要原始图像的参与,为盲水印算法。实验结果证明,该算法能有效抵抗JPEG压缩、加噪、剪切、滤波等常见攻击,而且在绿色分量中嵌入水印比在红色和蓝色分量中嵌入水印能更好地抵抗JPEG压缩的攻击。     

利用色彩分量相关性的彩色图像分形编码方法

论文提出了一种利用色彩分量相关性的彩色图像分形编码方法。该方法通过对图像的绿色分量用改进的分形编码方法编码,然后由绿、蓝、红三分量之间的相关性得相关系数,再对相关系数进行算术编码等三个步骤加快了彩色图像分形编码的速度,同时提高了恢复图像的质量,加大了压缩比。解码时用分形逆变换解得绿色分量,再由这个色彩分量和重构的相关系数解出另两个色彩分量,最后由三种分量共同恢复图像。大量实验表明,所提出的方法对于任何图像都有良好的效果,尤其适用于中低信噪比的情形。该方法对于有的图像超过了JPEG标准。     

基于RGB色彩模型相关模板的彩色人头图像编码

基于彩色人头图像RGB色彩模型色彩分量之间的相关性,提出一种针对彩色人头图像压缩编码的方法。该方法将彩色人头图像的面部特征区域用一种快速且较精确的方法提取出来,对色彩分量G面部特征区域进行细致编码,而对面部特征以外的区域进行粗犷编码,结合在色彩分量R、B与G之间建立的相关模板,实现对彩色人头图像的分级编码。实验结果表明该方法既能获得较满意的重构图像效果,又可大大提高编解码的效率和压缩比。     

Natural colour mapping for multiband nightvision imagery

We present a method to give (fused) multiband night-time imagery a natural day-time colour appearance. For input, the method requires a false colour RGB image that is produced by mapping three individual bands (or the first three principal components) of a multiband nightvision system to the respective channels of an RGB image. The false colour RGB nightvision image is transformed into a perceptually decorrelated colour space. In this colour space the first order statistics of a natural colour image (target scene) are transferred to the multiband nightvision image (source scene). To obtain a natural colour representation of the multiband night-time imagery, the compositions of the source and target scenes should resemble each other to some degree. The inverse transformation to RGB space yields a nightvision image with a day-time colour appearance. The luminance contrast of the resulting colour image can be enhanced by replacing its luminance component by a grayscale fused representation of the three input bands.     

基于直方图和模糊C均值的彩色图像分割方法

提出一种基于HSV空间的直方图和模糊C均值(FCM)相结合的彩色图像分割算法.首先将彩色图像转化到HSV空间,考虑到该空间的奇异性,把图像中的像素点根据饱和度和亮度划分为奇异点和非奇异点,然后对非奇异点建立3D HSV颜色直方图,并用爬山算法筛选出峰值进行像素点FCM聚类,对奇异点则建立1D灰度直方图,筛选出峰值进行直方图FCM聚类,最后合并两种分割结果.实验结果表明,该方法对彩色图像能够有效地提取目标物体,具有一定鲁棒性.     

Applications of ICA for the enhancement and classification of polarimetric SAR images

Independent components analysis (ICA) based methods for polarimetric synthetic aperture radar (SAR) image speckle reduction and ground object classification are studied. Several independent components can be extracted from polarimetric SAR images using ICA directly. The component with lowest speckle index is regarded as the scene after speckle reduction. The disadvantage of this method is that only one image is kept and most polarization information will be lost. In this paper, we use ICA‐sparse‐coding shrinkage (ICA‐SPS) based speckle reduction method, which is implemented on each individual image and can keep polarization information. It is carried out on the combined channels obtained by Pauli‐decomposition rather than original polarization channels in order to keep relative phase information among polarization channels and get better performance. After ICA‐SPS, the effect of speckle suppression on SAR image classification can be compared favourably with other methods by combining the channels into a false colour image. At last, a new ICA‐based classification method is presented. In this method, four independent components are separated by ICA from five polarization and combined channels. One of these independent components which includes little ground object information is regarded as speckle noise and therefore be discarded. The remaining three components can be treated as subordination coefficients of three kinds of targets. A classified image can be obtained based on the components. And by composing these three channels in RGB colour pattern, a false colour image can be constructed.     

Numerical scheme for efficient colour image denoising

In this paper, we are interested by the enhancement of colour images, where we present a numerical scheme to implement a non-linear diffusion filter. This scheme is developed to denoise colour images corrupted by additive noise. The method is based on harmonic averaging that takes into account correlation between all colour components of the image by using a common gradient magnitude which can be computed by using the Di Zenzo idea, and a marginal gradient magnitude in order to conserve the self behaviour of each colour component. The proposed scheme is an efficient tool at image selective smoothing in presence of strong noise. This analysis shows that our method performs better than some related works, and particularly in avoiding colour artifacts.     

Data association and occlusion handling for vision-based people tracking by mobile robots

This paper presents an approach for tracking multiple persons on a mobile robot with a combination of colour and thermal vision sensors, using several new techniques. First, an adaptive colour model is incorporated into the measurement model of the tracker. Second, a new approach for detecting occlusions is introduced, using a machine learning classifier for pairwise comparison of persons (classifying which one is in front of the other). Third, explicit occlusion handling is incorporated into the tracker. The paper presents a comprehensive, quantitative evaluation of the whole system and its different components using several real world data sets.     

Robust and transparent watermarking scheme for colour images

In this study, a robust and transparent watermarking scheme for colour images is proposed. The colour features for the human visual system are utilised to design the colour watermarking scheme. Through the exploitation of the perceptual redundancy of colour images, the proposed watermarking scheme is perceptually tuned to embed and detect the watermark in the perceptually significant sub-bands of luminance and chrominance components of colour images in the wavelet domain. The employment of the uniformity in the uniform colour space and the masking effect mainly due to local variations in luminance magnitude leads to that the perceptual redundancy of colour images can be measured. By using the estimated perceptual redundancy in the form of error visibility thresholds of wavelet coefficients of the colour image, high strength watermarks are invisibly embedded into coefficients of the host colour image for resisting compression and malicious attacks. Simulation results show that the estimation of perceptual redundancy is helpful to the design of the watermarking scheme for colour images. The performance in terms of robustness and transparency of the proposed watermarking scheme is superior to that of the existing scheme.     

A New QEM for Parametrization of Raster Images

We present an image processing method that converts a raster image to a simplical two‐complex which has only a small number of vertices (base mesh) plus a parametrization that maps each pixel in the original image to a combination of the barycentric coordinates of the triangle it is finally mapped into. Such a conversion of a raster image into a base mesh plus parametrization can be useful for many applications such as segmentation, image retargeting, multi‐resolution editing with arbitrary topologies, edge preserving smoothing, compression, etc. The goal of the algorithm is to produce a base mesh such that it has a small colour distortion as well as high shape fairness, and a parametrization that is globally continuous visually and numerically. Inspired by multi‐resolution adaptive parametrization of surfaces and quadric error metric, the algorithm converts pixels in the image to a dense triangle mesh and performs error‐bounded simplification jointly considering geometry and colour. The eliminated vertices are projected to an existing face. The implementation is iterative and stops when it reaches a prescribed error threshold. The algorithm is feature‐sensitive, i.e. salient feature edges in the images are preserved where possible and it takes colour into account thereby producing a better quality triangulation.     

基于C#的图片点阵数据提取和转换软件的开发

针对嵌入式系统的GUI(Graphical User Interface)设计中对彩色图片和图标的点阵数据的需求,设计一种能从多种常见图片文件中提取点阵数据并转换格式的软件.开发过程采用基于.Net Framework 2.0的C#语言,采用完全面向对象的方法,将文件处理、数据提取、格式转换以及输入和输出等功能封装成一个图像处理类.在绣花机控制器的开发使用中表明,该软件使用方便、功能实用、性能良好,完全达到设计目的,满足了GUI设计的需求.     

Delineating compositionally different dykes in the Ulukışla basin (Central Anatolia,Turkey) using computer‐enhanced multi‐spectral remote sensing data

In the Uluk??la basin (Central Anatolia, Turkey) several geological mapping campaigns were carried out using conventional field methods to delineate compositionally different Middle–Upper Eocene dykes. However, complete and correct mapping of these dykes was hampered by rugged terrain, lack of road access, wide spatial dyke distributions with small exposures and diverse weathering of these dykes. For these reasons, Landsat‐5 Thematic Mapper (TM) satellite image of the study area was used to facilitate delineation of the exact boundaries of gabbroic, dioritic and trachytic dykes found in the area. Remotely sensed data were analysed using several image enhancement procedures, including colour composites, band ratios, principal components analysis (PCA), and Crosta technique. Results obtained from all the processes were examined, and it was found that dyke boundaries are best visible in the PCA123 image; RGB 731 colour composite; TM band ratio 5/7, 5/1, 4 combination; and 1457‐PC4 image obtained by Crosta technique. The alteration differences of three dyke groups are enhanced much better in the 1457‐PC4 image obtained by Crosta technique, which highlights the hydroxyl‐bearing minerals as white‐coloured pixels. Using computer‐enhanced multi‐spectral remote sensing data, we were able to map the boundaries and spatial distributions of compositionally different dykes, which otherwise is an overwhelmingly difficult task to achieve using conventional field methods. In similar settings, remote sensing techniques applied in this study may provide an efficient and low‐cost alternative to time‐consuming and physically demanding field‐mapping campaigns.