Texture analysis methods have been used in various image processing tasks, such as image segmentation, recognition, shape analysis, texture synthesis, and image compression. When applying any of these methods, we assume that the input image has some textural characteristics. This paper addresses the problem of deciding whether an image has texture; in other words, whether texture-based methods are suitable for processing the image. We define a texture to have a spatially uniform distribution of local gray-value variations. A fast algorithm for detecting regions that have texture according to this definition is presented. The performance of the method is demonstrated on several synthetic and natural images.

A neural network texture classification method is proposed in this paper. The approach is introduced as a generalization of the multichannel filtering method. Instead of using a general filter bank, a neural network is trained to find a minimal set of specific filters, so that both the feature extraction and classification tasks are performed by the same unified network. The authors compute the error rates for different network parameters, and show the convergence speed of training and node pruning algorithms. The proposed method is demonstrated in several texture classification experiments. It is successfully applied in the tasks of locating barcodes in the images and segmenting a printed page into text, graphics, and background. Compared with the traditional multichannel filtering method, the neural network approach allows one to perform the same texture classification or segmentation task more efficiently. Extensions of the method, as well as its limitations, are discussed in the paper.

With the current rapid growth in multimedia technology, there is an imminent need for efficient techniques to search and query large image databases. Because of their unique and peculiar needs, image databases cannot be treated in a similar fashion to other types of digital libraries. The contextual dependencies present in images, and the complex nature of two-dimensional image data make the representation issues more difficult for image databases. An invariant representation of an image is still an open research issue. For these reasons, it is difficult to find a universal content-based retrieval technique. Current approaches based on shape, texture, and color for indexing image databases have met with limited success. Further, these techniques have not been adequately tested in the presence of noise and distortions. A given application domain offers stronger constraints for improving the retrieval performance. Fingerprint databases are characterized by their large size as well as noisy and distorted query images. Distortions are very common in fingerprint images due to elasticity of the skin. In this paper, a method of indexing large fingerprint image databases is presented. The approach integrates a number of domain-specific high-level features such as pattern class and ridge density at higher levels of the search. At the lowest level, it incorporates elastic structural feature-based matching for indexing the database. With a multilevel indexing approach, we have been able to reduce the search space. The search engine has also been implemented on Splash 2-a field programmable gate array (FPGA)-based array processor to obtain near-ASIC level speed of matching. Our approach has been tested on a locally collected test data and on NIST-9, a large fingerprint database available in the public domain.

There is a substantial interest in retrieving images from a large database using the textual information contained in the images. An algorithm which will automatically locate the textual regions in the input image will facilitate this task; the optical character recognizer can then be applied to only those regions of the image which contain text. We present a method for automatically locating text in complex color images. The algorithm first finds the approximate locations of text lines using horizontal spatial variance, and then extracts text components in these boxes using color segmentation. The proposed method has been used to locate text in compact disc (CD) and book cover images, as well as in the images of traffic scenes captured by a video camera. Initial results are encouraging and suggest that these algorithms can be used in image retrieval applications.

Multichannel filtering has been shown by many researchers to provide good features for texture segmentation and classification. In this paper the authors exploit neural networks to construct optimal filters and to combine the outputs of these filters for the classification of known textures. The authors use the neural network training together with node pruning, so that both the classification error and the number of filters or, equivalently, the number of features, are minimized. The performance of the neural network classifier is demonstrated an several experiments involving classification of natural textures. The authors study the effects of using different sized filters with different network configurations. The authors show that the number of filters, and, therefore, the processing time, can be greatly reduced while preserving the classification accuracy, using the proposed scheme compared to using a general set of filters (e.g., Gabor filters).