The study of the spectral reflective properties of a surface is one of the most important areas in the study of natural and manufactured objects. In scientific and practical problems, there is a need to evaluate the spectral properties of the surface under study from images obtained by digital RGB cameras. The article discusses the model of a digital camera from the side of image formation, as a spectral device. The mathematical model allows us to evaluate the possibility of using RGB images to estimate the values of the spectral characteristics of the surface reflection of the objects under study. Brick products are studied in this article. Based on the proposed image formation model, a technique is proposed for estimating the spectral reflectance of a brick surface based on RGB images. To do this, it is proposed to obtain an image not only of the brick, but also of the illuminator, which is located next to the image acquisition area. Based on the proposed model and methodology, software was developed and an experimental verification of the assumption made was carried out. The experiment captured images of several bricks and a light source and obtained reliable results on the possibility of estimating the spectral reflectance of the brick surface for each RGB channel. Real images of the manufacturing process of brick products were used for verification. Images of some bricks without defects and with various types of defects (chips and cracks) are shown. It was found that the histograms of brightness distribution for parts of bricks with defects and without defects differ from each other. That makes it possible to build an algorithm for detecting defects. The presented methodology for solving the problem of assessing the quality of brick products makes it possible to speed up and automate the quality control process.
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• brick
• assessment
• colour
• defect
• technical vision
• spectral reflectance
• technique