Image retrieval based on shape similarity by edge orientation autocorrelogram

This paper introduces a new feature vector for shape-based image indexing and retrieval. This feature classifies image edges based on two factors: their orientations and correlation between neighboring edges. Hence it includes information of continuous edges and lines of images and describes major shape properties of images. This scheme is effective and robustly tolerates translation, scaling, color, illumination, and viewing position variations. Experimental results show superiority of proposed scheme over several other indexing methods. Averages of precision and recall rates of this new indexing scheme for retrieval as compared with traditional color histogram are 1.99 and 1.59 times, respectively. These ratios are 1.26 and 1.04 compared to edge direction histogram.     

基于目标形状的图像检索

针对已有的基于形状的图像检索中目标形状描述方法的不足对其进行改进。首先对目标图像进行一系列预处理,得到图像的外部轮廓,利用改进的霍夫变换提取目标轮廓的线性特征;然后引入成对几何特征即有向相对角和有向相对位置来描述图像的形状;最后利用直方图相交算法衡量图像特征间的相似度。实验证明,利用本文改进的方法所描述的形状属性来检索数据库中的图像具有较高的效率。     

Statistical framework for image retrieval based on multiresolution features and similarity method

The advent of large scale digital image database leads to great challenges in content-based image retrieval (CBIR) method. The CBIR is considered an active area of research; however, it comprises a strong backdrop for new methodologies and system implementations. Hence, many research contributions focus on these techniques to enable higher image retrieval accuracy while preserving the low level computational complexity. This paper proposes a CBIR method, which is based on an efficient combination of multiresolution based color and texture features. This paper considers color autocorrelogram of the hue(H) and saturation(s) components of HSV color space for color features, and value(V) component of HSV color space for texture features. These two image features are extracted by computing co-occurrence matrix at optimum level image, which is the basis for the formation of feature vector. Though the optimum level is constructed based on wavelet transform, which contains a few dominant wavelet coefficients. The efficiency of the proposed system is tested with standard image databases, and the experimental results show that the proposed method achieves better retrieval accuracy at optimum level; moreover, the proposed method is very fast with low computational load. The obtained results are compared with existing techniques such as orthogonal polynomial model, multiresolution with BDIP-BVLC method and GLCM based system, and results reveal that the proposed method outperforms the existing methods.     

Image retrieval by texture similarity

Accuracy and efficiency are the two important issues in designing content-based image retrieval systems. In this paper, we present an efficient image retrieval system with high performance of accuracy based on two novel features, the composite sub-band gradient vector and the energy distribution pattern string. Both features are generated from the sub-images of a wavelet decomposition of the original image. A fuzzy matching mechanism based on energy distribution pattern strings serves as a filter to quickly remove undesired images in the database from further consideration. The images passing the filter will be compared with the query image based on composite sub-band gradient vectors which are extremely powerful for discriminating detailed textures. Through several extensive experiments by exercising our prototype system with a database of 2400 images, we demonstrated that both high accuracy and high efficiency can be achieved at the same time by our approach.     

A multiresolution descriptor for deformable 3D shape retrieval

In this paper, we present a spectral graph wavelet framework for the analysis and design of efficient shape signatures for nonrigid 3D shape retrieval. Although this work focuses primarily on shape retrieval, our approach is, however, fairly general and can be used to address other 3D shape analysis problems. In a bid to capture the global and local geometry of 3D shapes, we propose a multiresolution signature via a cubic spline wavelet generating kernel. The parameters of the proposed signature can be easily determined as a trade-off between effectiveness and compactness. Experimental results on two standard 3D shape benchmarks demonstrate the much better performance of the proposed shape retrieval approach in comparison with three state-of-the-art methods. Additionally, our approach yields a higher retrieval accuracy when used in conjunction with the intrinsic spatial partition matching.     

基于色彩与形状信息特征的图像检索算法研究

针对单独用颜色特征并不能很好地表达图像内容的问题,提出了综合利用颜色和形状特征进行图像检索的方法。由于颜色直方图无法表达空间分布信息,因此采用的颜色特征为颜色自相关图,并对色调进行重叠量化。而形状特征采用边缘方向直方图,并对方向进行重叠量化。仿真实验表明,综合利用颜色和形状特征比单独用颜色和形状特征进行图像检索的效果要好,提高了图像检索的查准率。     

Generalized multidimensional orthogonal polynomials withapplications to shape analysis

A technique using the generalized multidimensional orthogonal polynomials (GMDOP) for 2-D shape analysis is proposed. In shape analysis, spatial invariances (i.e. translational invariance, scaling invariance, rotational invariance, etc.) are important requirements for a shape analysis algorithm. The described technique provides not only the three invariant properties but also mirror-image rotational invariance and permutational invariance. Experimental results supporting the theory are presented     

Image filtering using multiresolution representations

It is shown how multiresolution representations can be used for filter design and implementation. These representations provide a coarse frequency decomposition of the image, which forms the basis for two filtering techniques. The first method, based on image pyramids, is used for approximating the convolution of an image with a given mask. In this technique, a filter is designed using a least-squares procedure based on filters synthesized from the basic pyramid equivalent filters. The second method is an adaptive noise reduction algorithm. An optimally filtered image is synthesized from the multiresolution levels, which in this case are maintained at the original sampling density. Individual pixels of the image representation are linearly combined under a minimum mean square error criterion. This uses a local signal-to-noise ratio estimate to provide the best compromise between noise removal and resolution loss     

基于边缘显著区域和结构相似度的图像视觉效果评价

图像的大部分结构信息都集中在了边缘,在进行边缘检测时滤除一些与图像计算不相关的信息,可减少计算中的数据量,使得计算更加便捷;在结构属性上也得到了很好的保留,因此边缘检测方法在图像视觉效果评估上是可行的。人眼对于一幅图像的视觉并不是每一个图像区域都具有同等的视觉重要性。可以建立一种数学方法,提取图像中的视觉重要区域,对这些区域进行视觉效果评价。选取基于结构相似度方法作为最终评价方法,得到了一种全参考图像质量评价算法。最后将实验结果与3个图像评价库的参考结果进行拟合,得到的结果与其他算法相比表明,该算法更加符合人眼的视觉效果特性。     

Image enlargement based on a step edge model

In compiling a multimedia document we often need to enlarge the size of an image. The traditional pixel repetition method tends to make the edges jagged. On the other hand, the interpolation-based methods tend to make the edges blurry in the enlarging process. In this paper we propose an image magnification method based on a step edge model. Using the model, we are able to define a straight step edge segment with four parameters. In enlarging a digital image, we first derive the parameter values for its step edge segments. This is like extracting the step edges in the corresponding continuous image. Then we re-digitize the step edges in the continuous image with a finer grid to obtain an enlarged image. In this way, the step edges are able to stay well defined after they are enlarged. The experiments show that in both visual comparison and quantitative analysis, the results produced by the suggested step edge model-based approach are consistently and significantly better than that produced by pixel repetition and bilinear interpolation.     

Non-symmetric correspondence analysis with ordinal variables using orthogonal polynomials

Non-symmetrical correspondence analysis (NSCA) is a useful tool for graphically detecting the asymmetric relationship between two categorical variables. Most of the theory associated with NSCA does not distinguish between a two-way contingency table of ordinal variables and a two-way one of nominal variables. Typically, singular value decomposition (SVD) is used in classical NSCA for dimension reduction. A bivariate moment decomposition (BMD) for ordinal variables in contingency tables using orthogonal polynomials and generalized correlations is proposed. This method not only takes into account the ordinal nature of the two categorical variables, but also permits for the detection of significant association in terms of location, dispersion and higher order components.     

Image steganography using deep learning based edge detection

This paper introduces a deep learning-based Steganography method for hiding secret information within the cover image. For this, we use a convolutional neural network (CNN) with Deep Supervision based edge detector, which can retain more edge pixels over conventional edge detection algorithms. Initially, the cover image is pre-processed by masking the last 5-bits of each pixel. The said edge detector model is then applied to obtain a gray-scale edge map. To get the prominent edge information, the gray-scale edge map is converted into a binary version using both global and adaptive binarization schemes. The purpose of using different binarization techniques is to prove the less sensitive nature of the edge detection method to the thresholding approaches. Our rule for embedding secret bits within the cover image is as follows: more bits into the edge pixels while fewer bits into the non-edge pixels. Experimental outcomes on various standard images confirm that compared to state-of-the-art methods, the proposed method achieves a higher payload.