Efficiently Storing Well-Composed Polyhedral Complexes Computed Over 3D Binary Images

A 3D binary image I can be naturally represented by a combinatorial-algebraic structure called cubical complex and denoted by Q(I), whose basic building blocks are vertices, edges, square faces and cubes. In Gonzalez-Diaz et al. (Discret Appl Math 183:59–77, 2015), we presented a method to “locally repair” Q(I) to obtain a polyhedral complex P(I) (whose basic building blocks are vertices, edges, specific polygons and polyhedra), homotopy equivalent to Q(I), satisfying that its boundary surface is a 2D manifold. P(I) is called a well-composed polyhedral complex over the picture I. Besides, we developed a new codification system for P(I), encoding geometric information of the cells of P(I) under the form of a 3D grayscale image, and the boundary face relations of the cells of P(I) under the form of a set of structuring elements. In this paper, we build upon (Gonzalez-Diaz et al. 2015) and prove that, to retrieve topological and geometric information of P(I), it is enough to store just one 3D point per polyhedron and hence neither grayscale image nor set of structuring elements are needed. From this “minimal” codification of P(I), we finally present a method to compute the 2-cells in the boundary surface of P(I).     

Digital Topology: Regular Sets and Root Images of the Cross-Median Filter

In the study of topological properties of digital images, which is the central topic of digital topology, one is often interested in special operations on object boundaries and their properties. Examples are contour filling or border following. In classical topology there exists the strong concept of regularity: regular sets in R² show no exotic behaviour and are extensively used in the theory of boundary value problems. In this paper we transfer the concept of regularity to digital topology within the framework of semi-topology. It is shown that regular open sets in (a special) semi-topology can be characterized graphically. A relationship between digital topology and image processing is established by showing that regular open digital sets, interpreted as digital pictures, are left unchanged when the cross-median filter is applied.     

A New Fuzzy Connectivity Measure for Fuzzy Sets

Fuzzy set theory constitutes a powerful representation framework that can lead to more robustness in problems such as image segmentation and recognition. This robustness results to some extent from the partial recovery of the continuity that is lost during digitization. In this paper we deal with connectivity measures on fuzzy sets. We show that usual fuzzy connectivity definitions have some drawbacks, and we propose a new definition that exhibits better properties, in particular in terms of continuity. This definition leads to a nested family of hyperconnections associated with a tolerance parameter. We show that corresponding connected components can be efficiently extracted using simple operations on a max-tree representation. Then we define attribute openings based on crisp or fuzzy criteria. We illustrate a potential use of these filters in a brain segmentation and recognition process.

灰度烟支图像的二值化算法

在烟支计数的实际应用中,为了后续的计数,需要对灰度烟支图像二值化。由于烟支图像中烟支小而多,烟支之间的间隔小,使用常用的阈值选取算法来二值化烟支图像并不能取得好的效果。本文根据Pun的最大熵算法提出了一种改进的局部最大熵均值综合阈值选取方法。本文的方法把整个烟支图像分成小区域,在每一个区域中综合考虑最大熵和区域域灰度均值来得到最优的阈值。实验结果表明了此算法的有效性。     

保持二值图像连通性的缩小算法

针对二值图像进行大因子缩小时容易产生连通性丢失的问题,提出一种保持连通性的缩小算法.将二值图像划分成互不相交的矩形区域,对光滑区域的像素根据人眼视觉系统进行处理,对边缘区域的像素根据人眼视觉系统和局部邻域的连通性进行处理,并通过保持连通性来保持图像的拓扑结构,得到拓扑结构较好的缩小图像.实验结果表明,与已有算法相比,文中算法能够在保持形状的情况下兼顾图像的拓扑结构.     

基于分解的灰度图像二维阈值选取算法

作为一维Otsu法的推广, 二维Otsu法综合考虑了像素点的灰度信息及其邻域灰度的均值信息, 可以有效地滤除噪声. 其快速算法采用递归的方式构建查找表, 将算法的时间复杂性由OL4降到OL2. 提出基于分解的阈值选取算法, 求解两个一维Otsu法的阈值来替代原始的二维Otsu法的最佳阈值. 指出在原算法的假设成立的条件下, 该方法可以得到与原二维Otsu法相同的分割阈值, 而算法的时间复杂性可以进一步降低到OL. 而在实际中, 原算法的假设一般不成立. 本文的实验结果表明此时该阈值选取方法也可以在保证原二维Otsu算法良好的抗噪性的前提下, 计算阈值所需的时间更短、空间更小, 且阈值化结果也可以达到或优于二维Otsu算法的结果.     

图像细化及其连通性保持的方法研究

利用数学形态学的方法对电力工程图纸进行细化的问题进行了研究,给出了具体的算法步骤,通过实验获得了符合要求的细化图像。对于某些细化后会产生空洞、断点的原始图像,需要对细化后的图像运用闭运算进行填充以保持细化后图像的连通性。     

数字图像的公开水印技术

基于领域中象素的相关性，提出一种将水印嵌入数字图像的空域的公开水印技术，首先，在图像的空域中，用密钥随机地选取一些图像象素及它们的领域，并将领域听象素排序，然后，通过调整被选象素与邻域中其它象素的大小关系来隐藏水印信息，为了提高水印的稳健性，将其重复嵌入，实验结果表明，文中方法对通常的图像处理操作是隐健的，特别地，当JPEG压缩比达1：13时，提取的水印仍可识别。     

Binarization and Multithresholding of Document Images Using Connectivity

Thresholding is a common image processing operation applied to gray-scale images to obtain binary or multilevel images. Traditionally, one of two approaches is used: global or locally adaptive processing. However, each of these approaches has a disadvantage: the global approach neglects local information, and the locally adaptive approach neglects global information. A thresholding method is described here that is global in approach, but uses a measure of local information, namely connectivity. Thresholds are found at the intensity levels that best preserve the connectivity of regions within the image. Thus, this method has advantages of both global and locally adaptive approaches. This method is applied here to document images. Experimental comparisons against other thresholding methods show that the connectivity-preserving method yields much improved results. On binary images, this method has been shown to improve subsequent OCR recognition rates from about 95% to 97,5%. More importantly, the new method has been shown to reduce the number of binarization failures (where text is so poorly binarized as to be totally unrecognizable by a commercial OCR system) from 33% to 6% on difficult images. For multilevel document images, as well, the results show similar improvement.     

基于灰度频率与空间连通性的运动目标检测

笔者提出一种基于灰度频率与空间连通性的运动目标检测算法。算法过程为采用初始或前一状态的前景比例值计算本帧灰度频率统计下的阈值,然后用该阈值对灰度图像进行二值化并统计二值图中不具有连通性的目标点,对于每一灰度图中首次独立点数量确定收敛方向,非首次独立点数量确定收敛完成。通过实验证明,本文算法针对不同实际场景均能有效准确检测运动目标。     

A New Algorithm for Hiding Gray Images Using Blocks

Abstract

As vast channels for communication, such as the Internet, become more popular, the security of digital media becomes a greater concern. Steganography is one of the techniques used to make detecting the transmitted data over channels more difficult, as hiding a message will reduce the probability of detecting this message. In this paper we suggest a new algorithm of steganography for hiding a gray image in one another. The cover is divided into blocks of equal sizes. Each block size equals the size of the embedding image.

The results drawn in this paper with the similarity equals 0.9717 are more improved and give the clear picture of the object.     

图像的局部约束变形技术

提出了一个基于局部约束的图像变形算法。该算法建立在一个新的C^2连续的变形模型上，局部约束包括单点约束和多点约束，用户可以交互地直接控制变形，实例计算表明，该算法十分灵活、简单和快速、变形效果很好。     

基于手机终端图像的数字水印技术

该文简要介绍了数字水印技术的基本原理。详细阐述了在手机终端的数字图像中进行信息隐藏的数字水印算法及提取算法。并编制了相应的程序对该算法进行了试验和分析。试验证明,该算法能有效地实现手机图像的版权保护。     

一种小波域数字水印算法

数字水印作为数字媒体版权保护的有效办法,近年来越来越为人们所重视。该文提出了一种基于小波变换在静止图像中嵌入数字水印的新算法;算法采用二值图像作为水印,首先利用二维离散小波变换对原始载体图像进行多级分解,然后置乱二值水印图象,将二值水印数据叠加到图象的低频小波系数上实现水印的嵌入,最后进行逆向小波变换生成嵌入水印后的图象。实验结果表明,该算法对JPEG有损压缩、滤波和噪声等水印攻击显示出较强的鲁棒性,取得了隐蔽性和鲁棒性的良好折衷。     

彩色灰度交叉融合的彩色图像渐变技术

研究图像渐变技术,存在着渐变过程不够自然以及渐变质量不够稳定的现象.为提高图像质量,针对上述图像问题,提出了一种新的彩色图像渐变技术,把渐变过程分为两个阶段,每个阶段分别进行彩色图像的灰度图转换和色彩饱和度分量调节.采用了一种新的非线性插值算法,与线性算法相比,渐变效果明显改善;与其它非线性算法相比,渐变的效果更加自然稳定,同时渐变处理的代价较小.实验结果表明,产生的渐变序列更加自然、平滑,图像效果好,同时渐变的效果有非常好的适应性.     

一种改进的数字图像置乱方法

图像置乱技术利于图像的保护,有效地保护数字图像内容为目的,结合Rijndael算法理论,提出了一种新的图像置乱算法.算法在原Rijndael算法的密钥扩展方案上进行了改进,综合运用了像素值置乱、像素位置乱、块置乱等技术,增强了图像置乱的效果.同时,算法改进了种子密钥的长度策略,使其与待加密图像的像素个数相等,以便适应于各种尺寸的数字图像,并有效提高了算法执行效率.采用图像相似度和图像直方图的评价方法对置乱的效果进行仿真计算.计算机仿真结果表明,与传统方法相比,算法对图像置乱简单高效,达到了很好的效果.     

Image-adaptive and Robust Digital Wavelet-domain Watermarking for Images

We propose a new frequency domain wavelet based watermarking technique. The key idea of our scheme is twofold： multire solution representation of image and odd-even quantization embedding/extracting watermark. Because many complementary watermarks need to be hidden, the watermark image designed is image-adaptive. The meaningful and complementary watermark images was embedded into the original image （host image） by odd-even quantization modifying coefficients, which was selected from the detail wavelet coefficients of the original image, if their magnitudes are larger than their corresponding Just Noticeable Difference thresholds. The tests show good robustness against best-known uttacks such as noise addition, image compression, median filtering, clipping as well as geometric transforms. Further research may improve the performance by refining JND thresholds.     

一种改进的TNAM灰度图像表示算法研究

图像表示在机器人、图像处理、模式识别等领域里是一个非常重要的研究内容之一.以流行的线性四元树表示方法和TNAM表示方法为研究对象,提出一种改进的TNAM灰度图像表示算法,并对算法的存储结构和总数据量进行了分析.理论分析和实验结果均表明:与流行的线性四元树表示方法和TNAM表示方法相比.改进的TNAM表示方法能更有效地减少数据存储空间,是灰度图像模式表示的一种良好表示方法.     

一种基于灰度数学形态学的水印算法

本文根据灰度图像数学形态学的特点以及小波的多尺度分辨特性,提出了一种鲁棒性较好的水印算法。首先,对载体图像和水印信息做预处理,第一个预处理是将载体图像做小波分解,分解的级数由水印信息量来确定,第二个预处理是对水印信息进行置乱;然后,对于小波分解得到的低频信息进行膨胀和腐蚀,并将膨胀的结果减去小波低频信息,同时将低频信息减去腐蚀的结果;接下来,在上一步得到的两个结果里同时嵌入有意义的水印;最后,利用小波逆变换重构含水印图像。实验结果证明,这个算法具有比较好的抗攻击性、不可见性。     

Polygonal Representations of Digital Sets

In the context of discrete curve evolution the following problem is of relevance: decompose the boundary of a plane digital object into convex and concave parts. Such a decomposition is very useful for describing the form of an object, e.g. for shape databases. Although the problem is relatively trivial in ordinary plane geometry, in digital geometry its statement becomes a very difficult task due to the fact that in digital geometry there is no simple set-complement duality. The paper is based on results given by Hübler et al. The main new contribution of the paper is the generalization of the concepts introduced by these authors to nonconvex sets. The digital geometric low level segmentation of the boundary of a digital object can be used as a starting basis for further reduction of the boundary by means of discrete evolution.