Similarity-based image retrieval method using wavelet transformation and its application to image database of historical objects in Japan

本课题的目的是为基于内容的图像数据库检索提供一种统一的基于小波变换的检索方案。该方案的两个主要组成部分如下：1）使用正交离散小波变换（DWT）的图像的层次分解：DWT分解图像为三个方向选择的细节图像和一个近似图像。分解过程可以递归地应用于近似图像以产生下一级分辨率。因此，我们可以得到一个金字塔结构的子图像与不同的分辨率对应的不同尺度。金字塔结构是图像边缘提取、纹理提取、纹理分割、形状提取等图像处理的基础。2）特征提取：从小波变换得到的子图像中提取图像的特征，例如，利用高阶局部自相关作为特征，对示例图像、形状、用户构造的草图和图纸进行检索。对于纹理检索，我们提出了新的功能计算的小波系数的详细子图像。在此基础上，我们开发了一个日本各地历史文物图像数据库的原型系统。该数据库包含日本历史博物馆收藏的日本传统文物、传统绘画、传统图案、传统乐器等，可根据示例图像、用户制作的草图、纹理等进行相似性检索，并可进行交互式组合。当用户对检索需求不明确或对数据库中的信息不熟悉时，系统支持浏览式检索。通过对数百幅图像的实验，显示出良好的性能。

The aim of this project is to provide a unifying scheme based on wavelet transform for content-based retrieval of image database. Two main components of the scheme are as follows :1)Hierarchical decomposition of images using orthogonal discrete wavelet transform (DWT) : DWT decomposes an image into three orientation selective detail images and an approximate image. The decomposition process can recursively be applied to the approximate image to produce the next level of the resolution. Thus we can obtain a pyramid structure of subimages with various resolutions corresponding to the different scales. It should be noted that the pyramid structure is the basis for image processing such as edge extraction, texture extraction, texture segmentation, shape extraction, and so on.2)Feature extraction : We extract features of an image from the subimages obtained by DWT.For example, we use the higher-order local autocorrelation as features for retrieval by example image, shape, user-constructed sketches and drawings. For retrieval by texture, we proposed new features computed from the wavelet coefficients of detailed subimages. These features are stored in the database.Based on this scheme, we have developed a prototype system of an image database of the historical objects of various places in Japan. This database includes classical pictures, patterns, and instruments, which are Japanese heritages and/or legacy objects collected in the National Museum of Japanese History.The system allows similarity retrieval based on example images, user-constructed sketches and drawings, textures, and interactive combinations of these. Then the system supports retrieval by browsing which is needed when users are vague about their retrieval needs or unfamiliar with the information available in the database. Experiment with hundreds of images showed good performance.