A Fourier domain directional filtering method for analysis of collagen alignment in ligaments

Collagen fibers and their component fibrils make up the protenaceous " backbone" of most tissues and provide the majority of their resistance to tensile loading. Spatial orientation of collagen fibrils is an important factor in determining tissue properties. This is particularly true in ligament tissue, since ligaments must be loose enough to allow joints to move but tight enough to prevent joint surfaces from separating. A method is presented here to reproducibly quantify this collagen arrangement, which should be useful in studies on ligament healing and growth.     

Quantitative analysis of the fine vascular anatomy of articularligaments

An image analysis technique has been developed to quantitatively describe the fine vascular patterns observed in ligament tissue. The longitudinal orientational distribution and total vessel volume of India-ink-perfused blood vessel segments in normal and healing ligaments were determined. The methods involved special vascular preparation of adult rabbit knee medial collateral ligaments (MCL) by India-ink perfusion. Black and white microscope images of ink-perfused tissue sections were subjected to a thresholding procedure to binarize digitized ligament images, which were then skeletonized and analyzed for directional distribution based on the least-squares technique. Analysis of medial collateral ligaments in New Zealand White rabbits using this method has shown that scarred tissue is more vascular and has a more chaotic angular distribution of blood-vessel segments than normal ligament tissue.     

Toward robust analysis of satellite images using mapinformation-application to urban area detection

With the rapid development of remote sensing, digital image processing has become an important tool for the quantitative and statistical analysis of remotely sensed images. These images most often contain complex natural scenes. The robust interpretation of such images requires the use of different sources of information about the scenes under consideration. This paper presents an integrated approach to robust analysis of SPOT images with the aid of map information as well as a priori knowledge about the contextual information of images. Markov random field theory and the Bayes formula are used to formulate the image analysis problem as a problem of optimization of an objective function, which in turn permits the application of various existing optimization algorithms to solve the problem. To increase the robustness of the result, several techniques are proposed to effectively use map information and image contextual information. The first one is concerned with the estimation of the parameters in the objective function with the help of these two sources of information. The second one is the integration of map information in Bayes image modeling using a Markov random field. The third one is a new optimization algorithm which takes into account map information and image contextual information by means of a feedback control scheme. The last technique proposed to increase the robustness of the result is concerned with the fusion of several (intermediate) analysis results by again using map knowledge and image contextual information for the estimation of the reliability of these results     

Extracellular Matrix Control of Collagen Mineralization In Vitro

Collagen biomineralization is a complex process and the controlling factors at the molecular level are still not well understood. A particularly high level of spatial control over collagen mineralization is evident in the anchorage of teeth to the jawbone by the periodontal ligament. Here, unmineralized ligament collagen fibrils become mineralized at an extremely sharp mineralization front in the root of the tooth. A model of collagen biomineralization based on demineralized cryosections of mouse molars in the bone socket is presented. When exposed to metastable calcium and phosphate‐containing solutions, mineral re‐deposits selectively into the natively mineralized tissues with high fidelity, demonstrating that the extracellular matrix retains sufficient information to control the rate of mineralization at the tissue level. While solutions of simulated bodily fluid produce amorphous calcium phosphate within the tissue section, a more highly supersaturated solution stabilized with polyaspartic acid produces oriented, crystalline calcium phosphate with diffraction patterns consistent with hydroxyapatite. The model thus replicates both spatial control of mineral deposition, as well as the matrix‐mineral relationships of natively mineralized collagen fibrils, and can be used to elucidate roles of specific biomolecules in the highly controlled process of collagen biomineralization. This knowledge will be critical in the design of collagen‐based scaffolds for tissue engineering of hard‐soft tissue interfaces.     

Detection of stellate distortions in mammograms

Malignant densities in mammograms have an irregular appearance and frequently are surrounded by a radiating pattern of linear spicules. In this paper a method is described to detect such stellate patterns. This method is based on statistical analysis of a map of pixel orientations. If an increase of pixels pointing to a region is found, this region is marked as suspicious, especially if such an increase is found in many directions. Orientations of the image intensity map are determined at each pixel using a multiscale approach. At a given scale, accurate line-based orientation estimates are obtained from the output of three-directional, second-order, Gaussian derivative operators. The orientation at the scale at which these operators have maximum response is selected. If a line-like structure is present at a given site, this method provides an estimate of the orientation of this structure, whereas in other cases the image noise will generate a random orientation. The pixel orientation map is used to construct two operators which are sensitive to radial patterns of straight lines. Combination of the output of these operators using a classifier allows for detection of stellate patterns. Different classification methods have been compared and results obtained on a common database are presented. Around 90% of the malignant cases were detected at rate of one false positive (FP) per image.     

A unified image retrieval framework on local visual and semantic concept-based feature spaces

This paper presents a learning-based unified image retrieval framework to represent images in local visual and semantic concept-based feature spaces. In this framework, a visual concept vocabulary (codebook) is automatically constructed by utilizing self-organizing map (SOM) and statistical models are built for local semantic concepts using probabilistic multi-class support vector machine (SVM). Based on these constructions, the images are represented in correlation and spatial relationship-enhanced concept feature spaces by exploiting the topology preserving local neighborhood structure of the codebook, local concept correlation statistics, and spatial relationships in individual encoded images. Finally, the features are unified by a dynamically weighted linear combination of similarity matching scheme based on the relevance feedback information. The feature weights are calculated by considering both the precision and the rank order information of the top retrieved relevant images of each representation, which adapts itself to individual searches to produce effective results. The experimental results on a photographic database of natural scenes and a bio-medical database of different imaging modalities and body parts demonstrate the effectiveness of the proposed framework.     

基于自适应多特征融合的红外图像增强算法

针对红外图像纹理不清晰、亮度低、高噪声的问题,提出了一种自适应多特征融合的红外图像增强算法。首先,通过用自动线性映射的方法对14位红外图像进行有效特征提取得到了16位图像,提升了图像可视化效果。其次,引入广义反锐化掩模(Generalized Unsharp Masking, GUM)算法与带色彩恢复的多尺度视网膜(Multi-Scale Retinex with Color Restoration, MSRCR)增强算法联合处理的方法,获得图像不同尺度的有效信息,提升了图像的对比度。最后设计了自适应权重图,并结合图像金字塔结构的特性,对不同特征层进行有效信息的互补融合,提升了图像亮度,丰富了图像的纹理信息。实验结果表明,此算法有效提升了红外图像的对比度和视觉效果;相较于现有的几种算法,其平均梯度(Average Gradient, AG)约提升0.6%,峰值信噪比(Peak Signal-to-Noise Ratio, PSNR)约提升10%,图像的边缘信息有效率约提升11%,图像的清晰度约提升10%。     

结构保持的双边滤波极化SAR图像降噪

针对极化合成孔径雷达(Polarimetric Synthetic Aperture Radar, PolSAR)图像相干斑抑制时结构保持的难题,该文提出一种PolSAR图像的双边滤波算法：结构保持的双边滤波(SPBF)。该算法通过结合边缘结构特征和地物散射特性,增强对PolSAR图像结构信息的描述,减少滤波时图像结构信息的损失,实现滤波性能的提高。该算法首先使用边缘检测模板在极化总功率图像(Span)上提取边缘方向,实现自适应选择滤波方向窗;其次,采用Freeman-Durden分解获取像素的散射机制,并根据极化数据的统计分布特性获取地物散射的聚类标记;最终在所选的方向窗中,以聚类标记图为掩膜,利用改进的双边滤波算法对PolSAR数据进行相干斑抑制。真实SAR数据的实验结果表明,该方法能够有效抑制相干斑噪声,同时提高了对图像的边缘、强点目标和极化散射特性的保持能力。     

Compression of multispectral images by spectral classification andtransform coding

This paper presents a new technique for the compression of multispectral images, which relies on the segmentation of the image into regions of approximately homogeneous land cover. The rationale behind this approach is that, within regions of the same land cover, the pixels have stationary statistics and are characterized by mostly linear dependency, contrary to what usually happens for unsegmented images. Therefore, by applying conventional transform coding techniques to homogeneous groups of pixels, the proposed algorithm is able to effectively exploit the statistical redundancy of the image, thereby improving the rate distortion performance. The proposed coding strategy consists of three main steps. First, each pixel is classified by vector quantizing its spectral response vector, so that both a reliable classification and a minimum distortion encoding of each vector are obtained. Then, the classification map is entropy encoded and sent as side information, Finally, the residual vectors are grouped according to their classes and undergo Karhunen-Loeve transforming in the spectral domain and discrete cosine transforming in the spatial domain. Numerical experiments on a six-band thematic mapper image show that the proposed technique outperforms the conventional transform coding technique by 1 to 2 dB at all rates of interest.     

一种新的多尺度模型GLSA及其人脸识别的应用

考虑图像的近似信息和细节信息,提出了推广的线性尺度自回归(GLSA)多尺度模型。首先利用该模型建立不同尺度图像间的映射关系;其次使用原始图像及其小波分解结果得到模型中的参数以确定这种映射关系;最后根据该映射关系由低分辨率图像估计高分辨率图像。将该模型用于人脸识别处理,通过比较被测试图像的模型参数和训练集图像的模型参数确定被测试图像的类别。实验结果表明,使用GLSA模型估计得到的图像更加接近目标图像,以该模型为基础的人脸识别系统对光照的鲁棒性较强。     

Bayesian technique for image classifying registration

In this paper, we address a complex image registration issue arising while the dependencies between intensities of images to be registered are not spatially homogeneous. Such a situation is frequently encountered in medical imaging when a pathology present in one of the images modifies locally intensity dependencies observed on normal tissues. Usual image registration models, which are based on a single global intensity similarity criterion, fail to register such images, as they are blind to local deviations of intensity dependencies. Such a limitation is also encountered in contrast-enhanced images where there exist multiple pixel classes having different properties of contrast agent absorption. In this paper, we propose a new model in which the similarity criterion is adapted locally to images by classification of image intensity dependencies. Defined in a Bayesian framework, the similarity criterion is a mixture of probability distributions describing dependencies on two classes. The model also includes a class map which locates pixels of the two classes and weighs the two mixture components. The registration problem is formulated both as an energy minimization problem and as a maximum a posteriori estimation problem. It is solved using a gradient descent algorithm. In the problem formulation and resolution, the image deformation and the class map are estimated simultaneously, leading to an original combination of registration and classification that we call image classifying registration. Whenever sufficient information about class location is available in applications, the registration can also be performed on its own by fixing a given class map. Finally, we illustrate the interest of our model on two real applications from medical imaging: template-based segmentation of contrast-enhanced images and lesion detection in mammograms. We also conduct an evaluation of our model on simulated medical data and show its ability to take into account spatial variations of intensity dependencies while keeping a good registration accuracy.     

Information-theoretic analysis of interscale and intrascaledependencies between image wavelet coefficients

This paper presents an information-theoretic analysis of statistical dependencies between image wavelet coefficients. The dependencies are measured using mutual information, which has a fundamental relationship to data compression, estimation, and classification performance. Mutual information is computed analytically for several statistical image models, and depends strongly on the choice of wavelet filters. In the absence of an explicit statistical model, a method is studied for reliably estimating mutual information from image data. The validity of the model-based and data-driven approaches is assessed on representative real-world photographic images. Our results are consistent with empirical observations that coding schemes exploiting inter- and intrascale dependencies alone perform very well, whereas taking both into account does not significantly improve coding performance. A similar observation applies to other image processing applications.     

Statistical model-based algorithms for image analysis

In this paper, two-dimensional stochastic linear models are used in developing algorithms for image analysis such as classification, segmentation, and object detection in images characterized by textured backgrounds. These models generate two-dimensional random processes as outputs to which statistical inference procedures can naturally be applied. A common thread throughout our algorithms is the interpretation of the inference procedures in terms of linear prediction residuals. This interpretation leads to statistical tests more insightful than the original tests and makes the procedures computationally tractable. This paper also examines a computational structure tailored to one of the algorithms. In particular, we describe a processor based on systolic arrays that realizes the object detection algorithm developed in the paper.     

Gamut mapping optimization algorithm based on gamut-mapped image measure (GMIM)

This paper presented a novel gamut mapping optimization algorithm based on a special designed gamut-mapped image measure (GMIM). We formulated GMIM as an objective function in an iterative manner, where the iterative step changes based on the information weight which can be computed between the original image and the initial gamut-mapped images. A new metric, GMIM, is developed to compute the achromatic differences and the chromatic differences of the input images based on structural similarity index. For the achromatic part, we introduce the gradient information to detect the achromatic distortions between two images; the chromatic part aims to analyze the hue and chroma information. Further, the circular statistical theory is employed to calculate the hue value. In the iterative process, we change the iterative steps according to the information weight which can be computed by the information theory. The information map between images indicated regions in an image which human paid attentions to. Experimental results demonstrated that our new gamut mapping method can preserve the brightness, color, as well as detail information of the reference images.     

Texture analysis-based multi-focus image fusion using a modified Pulse-Coupled Neural Network (PCNN)

Multi-focus image fusion is an effective method of information fusion that can take a series of source images and obtain a fused image where everything is in focus. In this paper, a multi-focus image fusion method based on image texture that adopts a modified Pulse-Coupled Neural Network (PCNN) approach is proposed. First, the texture of an image is obtained by means of image cartoon and texture decomposition. An ignition image is then acquired by inputting the image textures into a modified PCNN. Ignition images are compared to each other to obtain an initial decision map. A small object detection and bilateral filter is then applied to the initial decision map to reduce noise and enable smoother processing. Finally, the source images and decision map are used to produce the fused image. Experimental results demonstrate that the proposed method effectively preserves the source images information while delivering good image fusion performance.     

Center symmetric local binary co-occurrence pattern for texture,face and bio-medical image retrieval

Content based image retrieval is a common problem for a large image database. Many methods have been proposed for image retrieval for some particular type of datasets. In the proposed work, a new image retrieval technique has been introduced. This technique is useful for different kind of dataset. In the proposed method, center symmetric local binary pattern has been extracted from the original image to obtain the local information. Co-occurrence of pixel pairs in local pattern map have been observed in different directions and distances using gray level co-occurrence matrix. Earlier methods have utilized histogram to extract the frequency information of local pattern map but co-occurrence of pixel pairs is more robust than frequency of patterns. The proposed method is tested on three different category of images, i.e., texture, face and medical image database and compared with typical state-of-the-art local patterns.     

一种面向对象的时间序列极化SAR图像变化检测方法

提出了一种改进的时间序列极化合成孔径雷达(SAR)图像变化检测方法。该方法首先使用简单线性迭代聚类算法对时间序列极化SAR图像进行过分割,得到时间序列图像的超像素一致表达。然后对各个超像素进行时间序列上的任意双时相交叉变化检测,得到包含时间序列图像变化信息的变化检测矩阵。最后根据变化信息对图像在时间序列上进行平滑滤波并生成动态变化图,对地物变化情况进行分析。实验结果表明,文中方法能够有效地检测和分析时间序列极化SAR图像的变化情况。     

基于双引导滤波的红外和可见光图像融合算法

图像融合是将多幅图像中有用或互补信息整合成一幅图像的过程。本文提出了一种基于引导滤波多尺度分解的红外和可见光图像融合算法。在传统的引导滤波图像融合算法的基础之上,利用双引导滤波器代替均值滤波器将源图像分解为小尺度纹理细节、大尺度边缘和基础图像;直接利用纹理细节及边缘层图像构建显著性映射图,用其代替额外的特征提取操作,可很好地突出源图像显著性信息的同时大大降低算法复杂度;利用显著性映射图、Sigmoid函数构造权重图,将源图像中具有视觉意义的信息注入到融合图像中;利用色彩模型转换融合方式,可更好保留图像的色彩信息。定性和定量实验结果证明,相比于传统的基于引导滤波的图像融合算法,本文算法的融合效果得到进一步提升。     

Controlling Familywise Error Rate for Matched Subspace Detection in Dynamic FDG PET

Detection of small lesions in fluorodeoxyglucose (FDG) positron emission tomography (PET) is limited by image resolution and low signal to noise ratio. We have previously described a matched subspace detection method that uses the time activity curve to distinguish tumors from background in dynamic FDG PET. Applying this algorithm on a voxel by voxel basis throughout the dynamic image produces a test statistic image or ldquomaprdquo which on thresholding indicates the potential locations of secondary or metastatic tumors. In this paper, we describe a thresholding method that controls familywise error rate (FWER) for the matched subspace detection statistical map. The method involves three steps. First, the PET image is segmented into several homogeneous regions. Then, the statistical map is normalized to a zero mean unit variance Gaussian random field. Finally, the images are thresholded at a fixed FWER by estimating their spatial smoothness and applying a random field theory maximum statistic approach. We evaluate this thresholding method using digital phantoms generated from clinical dynamic images. We also present an application of the proposed approach to clinical PET data from a breast cancer patient with metastatic disease.