基于脊波变换的金融汉字不变性特征提取方法

为了满足对多方向选择性的要求,提出一种基于脊波变换的手写体金融汉字的不变性特征提取方法。该方法首先利用Radon变换将原始图像的旋转转换成Radon域的环形移位,再利用傅里叶变换振幅具有平移不变性的特点,在Radon域应用一维傅里叶变换,得到的振幅矩阵具有旋转不变性,它对旋转不变特征提取是非常理想的;然后沿振幅矩阵行的方向执行一维多分辨小波变换,使得从频域适当的子带提取特征成为可能;从Ridgelet子带中提取均值、标准差和能量组成特征向量。通过实验的验证,该方法可以满足表单自动处理系统应用对手写体金融汉字识别的要求。     

面向彩色图像的尺度和旋转不变性特征提取方法及应用

提出一种面向彩色图像的尺度和旋转不变性特征提取方法,并在真实的场景识别中进行了应用。该方法是先对给定彩色图像的各组成平面分别进行Radon变换,然后对得到的Radon变换系数矩阵进行尺度不变性处理,接着对处理后的Radon变换系数矩阵用频率B样条小波进行1维小波变换,在所得到的脊波系数矩阵中计算均值和方差的同时,采用线性回归模型提取在不同的颜色组成平面下所有频率子波段之间的关系属性,最后将得到的特征进行旋转不变性处理,从而得到所提出的尺度和旋转不变性特征。在3个数据库上进行了实验,结果表明本文方法可靠有效。     

复脊波变换SAR图像去噪算法

在分析传统脊波变换去噪方法优缺点的基础上, 针对其不足, 提出一种基于复脊波变换的去噪方法。算法将传统脊波变换中的标量一维小波变换替换为二元树复小波变换, 使得脊波变换具有平移不变性; 然后, 对图像采用冗余分块处理, 使得处理结果更平滑, 有效地提高了图像的峰值信噪比（PSNR）。仿真实验表明, 在SAR图像去噪应用中, 本方法能够更好地保留图像中的纹理信息, 处理结果优于传统脊波变换以及小波变换去噪方法。     

一种改进的综合纹理和形状特征的图像检索方法

提出一种利用小波进行综合纹理和形状特征的具有旋转、平移和尺度不变性的图像检索算法.使用角向矩加权方向定义图像的主方向来进行坐标轴的旋转矫正,得到图像的旋转不变性表示;采用具有平移和尺度不变性的小波变换对图像进行小波分解,利用各子带的能量作为纹理特征;利用小波分解的逼近子图重构图像并进一步利用Hu不变矩提取其形状特征.最后对纹理和形状特征进行高斯归一化,综合其特征进行检索.实验中对算法的尺度不变性、旋转不变性、平移不变性及对噪声的不敏感性进行了验证,实验结果证明了该算法具有更高的鲁棒性和查准率.     

基于NSST和RI-LPQ的纹理图像检索

针对采用单一方法提取图像特征时检索率不高的问题,结合非下采样剪切波变换(NSST)统计特征和旋转不变的局部相位量化(RI-LPQ)原理,提出一种纹理图像检索方法。非下采样剪切波不仅具有方向选择性及平移不变性,而且可以对图像进行有效的稀疏表示,与传统小波相比,可有效捕捉图像的边缘轮廓等纹理信息,与非下采样轮廓波相比,具有更高的计算效率。利用广义高斯分布函数对图像NSST高频子带系数的统计特征进行分析,RI-LPQ描述算子直接提取图像特征,采用具有权重系数的相似性测度公式对Brodatz图像库进行纹理图像检索。实验结果表明,与传统小波和轮廓波的方法相比,NSST统计特征方法的平均检索率分别提高4.77%和1.44%,纹理图像检索方法的平均检索率分别提高7.36%和1.98%。     

基于Radon变换和SWT的旋转不变纹理分类

提出了一种应用Radon变换和离散平稳小波变换(SWT)的旋转不变纹理分类算法。该方法首先对纹理图像进行Radon变换将旋转转化为平移,再用具有平移不变性的离散平稳小波对变换后的图像滤波并计算各子带的能量值组成旋转不变特征向量,最后利用支持向量机实现纹理图像的分类。将本方法与其它旋转不变纹理分类法进行比较,实验结果表明,提出的方法能有效地提高正确分类率。     

一类新的纹理谱描述子

在纹理元的基础上提出了一类新的纹理谱描述子,新的纹理谱描述子在3个方面作了改进：将像素的灰度差量化为4个值;量化区间根据纹理对比度自动确定,并保证量化值具有灰度线性不变性;利用相关性弱的8邻域像素构建纹理谱描述子,从而降低了纹理谱维数。定义了基于新的纹理谱描述子的光照、旋转不变性纹理特征。利用该特征对Outex纹理进行光照、旋转不变性分类,分类准确率高于基于局部二值模式的光照、旋转不变性纹理特征。     

基于LBP的尺度不变特征的描述和匹配算法

针对尺度不变特征变换(SIFT)算法计算复杂度高和匹配速度慢的难题,提出一种新的基于局部二进制模式(LBP)的尺度不变特征变换算法.首先采用高斯差分尺度空间检测局部极大值,利用圆形邻域统计梯度方向直方图来确定特征点的主方向,再通过坐标轴旋转避免图像旋转的计算代价;然后运用改进后的LBP算子求取特征点邻域的纹理信息,得到132比特的特征点描述子,有效地降低了描述子的计算复杂度;最后运用逻辑与运算对描述子进行特征点匹配.图像匹配实验结果表明,该算法具有尺度不变性、旋转不变性、仿射不变性和光照不变性等优良特性,在保证匹配正确率与SIFT和CS-LBP算法基本一致的情况下,运算速度优于以上2种算法,其中光照不变性明显优于SIFT算法.     

基于形状和纹理的图像检索

构造了Radon变换的不变量，提出一种新的基于形状和纹理的图像检索方法。对小波图像边缘提取Radon不变量作为形状特征，同时提取小波各频道能量作为纹理特征。然后将形状特征和纹理特征分别进行高斯归一化，计算图像形状和纹理的相似度。最后，利用形状和纹理相似度的加权和进行图像检索。试验结果表明该方法对噪声具有较强的鲁棒性，具有尺度、平移和旋转不变性。     

基于局部差分模式的不变性纹理分类

提出了局部差分变换和局部差分模式。局部差分变换具有灰度线性不变性,可消除光照变化对纹理分析的影响。基于局部差分变换的局部差分模式具有光照、旋转不变性和良好的多尺度分析能力。局部差分模式直方图可作为光照、平移、旋转不变性特征用于不变性纹理分类。实验表明,该方法的不变性纹理分类效果优于目前国际公认的基于LBP的方法。     

Log-polar wavelet energy signatures for rotation and scale invariant texture classification

Classification of texture images is important in image analysis and classification. This paper proposes an effective scheme for rotation and scale invariant texture classification using log-polar wavelet signatures. The rotation and scale invariant feature extraction for a given image involves applying a log-polar transform to eliminate the rotation and scale effects, but at same time produce a row shifted log-polar image, which is then passed to an adaptive row shift invariant wavelet packet transform to eliminate the row shift effects. So, the output wavelet coefficients are rotation and scale invariant. The adaptive row shift invariant wavelet packet transform is quite efficient with only O(n /spl middot/ log n) complexity. A feature vector of the most dominant log-polar wavelet energy signatures extracted from each subband of wavelet coefficients is constructed for rotation and scale invariant texture classification. In the experiments, we employed a Mahalanobis classifier to classify a set of 25 distinct natural textures selected from the Brodatz album. The experimental results, based on different testing data sets for images with different orientations and scales, show that the proposed classification scheme using log-polar wavelet signatures outperforms two other texture classification methods, its overall accuracy rate for joint rotation and scale invariance being 90.8 percent, demonstrating that the extracted energy signatures are effective rotation and scale invariant features. Concerning its robustness to noise, the classification scheme also performs better than the other methods.     

Rotation and gray scale transform invariant texture identificationusing wavelet decomposition and hidden Markov model

In this correspondence, we have presented a rotation and gray scale transform invariant texture recognition scheme using the combination of quadrature mirror filter (QMF) bank and hidden Markov model (HMM). In the first stage, the QMF bank is used as the wavelet transform to decompose the texture image into subbands. The gray scale transform invariant features derived from the statistics based on first-order distribution of gray levels are then extracted from each subband image. In the second stage, the sequence of subbands is modeled as a hidden Markov model (HMM), and one HMM is designed for each class of textures. The HMM is used to exploit the dependence among these subbands, and is able to capture the trend of changes caused by rotation. During recognition, the unknown texture is matched against all the models. The best matched model identifies the texture class. Up to 93.33% classification accuracy is reported     

基于Radon变换的纹理图像多尺度不变量分析算法

为了更好地进行图像纹理分析,提出了一种基于Radon变换的不变量纹理识别算法。该算法首先利用Radon变换将图像投影到1维空间,然后通过对投影数据进行一种平移和比例不变的自适应小波变换来构造出具有比例和平移不变性的图像的特征矩阵。这种通过对特征矩阵进行多尺度分析得到的多尺度能量特征不但具有平移、比例和旋转不变性,而且反映出了纹理图像在不同尺度上的能量分布特征。在特征提取完成以后,即可利用支撑向量机进行分类。同其他方法的比较说明,该算法可较好地描述纹理特征,并可完成纹理识别。     

基于尺度不变特征的脊波域量化水印算法

针对传统数字水印算法抵抗旋转、缩放等几何攻击能力较弱的问题,提出一种基于尺度不变特征的脊波域量化水印算法.利用尺度不变特征变换构造稳定的图像局部区域,对局部区域实施脊波变换,选择能量较大方向上的脊波细节系数,利用量化索引调制策略嵌入水印信息.仿真结果表明,该算法具有较好的检测性能,在抗压缩、叠加噪声、缩放、剪切等攻击方面具有较强的鲁棒性.     

一种快速旋转不变图像检索新方法

提出了一种新型快速旋转不变图像检索新方法.该方法首先对图像进行傅里叶变换和功率谱分解,提取功率谱的扇形区域能量和环形区域能量参数,并将其均值和标准差作为图像纹理特征.然后,利用谱能量分布特征把纹理的主方向旋转到0°,提取旋转后图像的共生矩阵参数和小波分解各子带图像统计参数作为基本特征.利用所提出的特征提取方法在两组分别包含25类单色自然纹理的图像库上进行检索试验.结果表明,该方法获得了良好的检索效果.     

A novel scale and rotation invariant texture image retrieval method using fuzzy logic classifier

A novel approach for content-based texture image retrieval system using fuzzy logic classifier is proposed in this paper. The novelty of this method is demonstrated by handling the complexity issues in texture image retrieval arising from rotation and scale variance. These issues are divided into four groups as non rotated non scaled, rotation invariant, scale invariant and scale and rotation invariant texture retrieval for retrieval performance analysis. Features of texture images are obtained using discrete wavelet transform based statistical features and gray level co-occurrence matrix based co-occurrence features. The fuzzy logic classifier is developed with Gaussian membership function with mean and standard deviations of the features. The retrieval performance improvement is carried out by considering various combinations of the features. The average retrieval rates for the four issues have been achieved at 99.40% with 40 features, 91% with 80 features, 65.2% with 40 features, and 63.4% with 65 features respectively. This method outperforms the existing methods in terms of average retrieval rate. The scale and rotation invariant texture retrieval is an incomparable work that has been demonstrated in the present paper.     

Rotation invariant features for color texture classification and retrieval under varying illumination

This article proposes a new quaternion-based method for rotation invariant color texture classification under illumination variance with respect to direction and spectral band. The color of an object varies according to the spectral power distribution, object-illumination, and viewing geometry of the light source. The quaternion representation of color is shown to be effective, which treats color channels as single unit rather than separate components. New texture signatures are extracted by calculating the norm of the Quaternion fourier spectrum. These signatures are proved to be invariant under image rotation and illumination rotation. Moreover, these features are also invariant to the color spaces. The robustness of different color spaces against varying illumination in color Texture classification with 45 samples of 15 outex texture classes are examined. Comparative results show that the proposed method is efficient in rotation invariant texture classification.