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CONCRETE PRODUCTS & CAST STONE84 CPI %u2013 Concrete Plant International %u2013 3 | 2025 www.cpi-worldwide.comConcrete paving stones are widely used as a decorative paving element. Its production technologies go back decades and are relatively conservative, that is, they have not undergone significant changes recently. World standards define numerous parameters of paving slabs that guarantee their reliability and durability. However, there is still no single standard that would objectively regulate the key aesthetic characteristic of the coating %u2013 the color of the face layer.In modern practice, color assessment usually comes down to a subjective requirement: %u201cThe color must correspond to the manufacturer%u2019s standard.%u201d But what exactly is meant by standard? Do all manufacturers have it, and is it defined the same? Are the standards the same at different plants of the same manufacturer? How and by whom is the finished product compared with this standard? These questions are relevant even for simple monochrome colors (yellow, red, etc.), and when making products with a mixture of colors, their importance increases many times over.This article proposes an approach to determining the objective parameters of the color of paving slabs and consider the following questions:%u2022 How to describe a color to fix it as a standard?%u2022 How to control whether the resulting color matches the selected standard?Requirements for measuring equipmentSince the purpose of the research is objective parameters, a means of measuring these parameters is needed that works according to a clear methodology. The key element of the proposed color control system is a computer vision complex that will analyze products both immediately on the wet side and on the dry side. The system must guarantee high-quality images of the entire pallet of products without color or illumination distortion. If there are local features of the installation site (type of lighting, background, reflections), they must be compensated in hardware or software so that the final image is uniform and normalized. It is important to ensure that installations are calibrated to obtain consistent data not only across different installations within the same plant, but also across different plants of the same manufacturer. Preparing a color referenceIn any production, a qualified quality manager can identify product samples that are considered typical representatives of the desired color scheme. From this point, the preparation of a standard for the system begins: the marking of samples selected as reference takes place.To turn a set of reference samples into a digital master, it is necessary to identify key parameters that are understandable to both humans and the computer vision system. The main stages of preparing a color standard are as follows.Selection of reference samplesA qualified quality specialist manually selects representatives of each required color.Bringing out pure colorsThe software system, knowing that the face layer consists of one or more color components, analyzes the image and selects individual pure colors, the mixing of which occurs in the texture layer. It is important to process the entire analyzed product molding field as a single space, otherwise the same colors on different molds will have different statistical characteristics.Definition of statistical parametersFor each selected pure color, its quantitative share in the texture layer is calculated, as well as the characteristic sizes of color zones. As a result of processing reference samples for each color, a set of parameters is formed that sufficiently fully describes the standard:%u2022 RGB codes of pure basic colors;%u2022 The percentage of each pure color in the image;%u2022 The characteristic size of color zones and their coverage of the image area, describing the pattern of color mixing.The physical meaning of the first two parameters is clear from the name. The latter is worth explaining separately. In the color pattern within the molding zone, closed zones of simiObjective parameters of paving stone colorQuatromatic LTD, London, EC4M 7LF, England n Evgeny Pashko, Quatromatic LTD, England