科研之友
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摘要
We present an overview of methods and applications of automatic characterization of the appearance of materials through colour and texture analysis. We propose a taxonomy based on three classes of methods (spectral, spatial, and hybrid) and discuss their general advantages and disadvantages. For each class we present a set of methods that are computationally cheap and easy to implement and that was proved to be reliable in many applications. We put these methods in the context of typical industrial environments and provide examples of their application in the following tasks: surface grading, surface inspection, and content-based image retrieval. We emphasize the potential benefits that would come from a wide implementation of these methods, such as better product quality, new services, and higher customer satisfaction. 1. Introduction Computer vision has been a topic of intense research activity for decades. The wide availability of imaging devices, as well as the continuously increasing computing power, has contributed to the development of successful applications in many areas: remote sensing, computer-aided diagnosis, automatic surveillance, crowd monitoring, and food control are just some examples [1]. Manufacturing is also an important sector that benefits from computer vision methods: robotics [2], process automation [3], and quality control [4] are typical applications in this context. Most of these applications share the same underlying problem: the automatic characterization of the visual appearance of the materials that one has to deal with in the various domains. This is particularly true for products with high aesthetic value [5, 6], such as natural stone [7], ceramic [8], parquet [9], and fabric [10, 11], to cite some. In such cases it is the visual appearance itself that largely determines the quality〞therefore the price〞of the material. The measurement of visual appearance can be considered a part of ※soft metrology,§ the aim of which is the objective quantification of the properties of materials that are determined by sensorial human response. In an increasingly competitive worldwide market, reliable and effective assessment of this feature is a key point to ensure high quality standard and the success of a company. Traditionally, the analysis of the visual appearance has been accomplished by skilled operators. This is a lengthy, tedious, scarcely reproducible, and largely subjective approach [12]. To overcome these issues many companies are abandoning manual procedures and moving towards automated computer vision systems, which in
- 出版日期2013
