# Approach to Automated Visual Inspection of Objects Based on Artificial Intelligence
## 2 Materials and Methods  
### Inspected Object  
The aim of the ongoing research at the Department of Automation and Production Systems is to find the optimal method for visual inspection of objects with a surface that is complicated to properly illuminate and then scan. One work from the department is described in [26]. In order to design a methodology for automated visual inspection of objects with specific properties, the selected test object was an automobile tire displayed in Figure 1. The main reason was the demand from industry for solving the situation in real operation and the fact that the elements on dark and matte objects in practice prove to be very difficult to detect. Other reasons were the complexity of the object, the occurrence of texts of various fonts, special characters and repeating elements, which are prerequisites for successful verification of the hypothesis associated with the elaborated task. Any car tire is generally manufactured out of a mixture of natural rubber (several types) with acids, artificial rubber made of polymers and additives. The tire undergoes a thermoforming process and subsequent vulcanization, in which the aforementioned additives determine the properties of the final product. The surface of the entire product is matte and black after production, which affects the difficulty of its lighting during the image acquisition in order to achieve optimal results. The inspected object--a car tire--is composed of two basic parts (in terms of functionality and position in the tire body), the read and the sidewall, and several additional parts. The tread is a key component of every tire in terms of functionality, as it is in contact with the road and, therefore, determines its main performance characteristics such as traction, rolling resistance, fuel consumption, external noise, etc. [22]. The second important part is the sidewall, which is characterized by specific properties and a reference surface, i.e., an area where manufacturers place a description/basic identification parameters of a specific tire:  
Figure 1: Object chosen for automated visual inspection methodology design. * DOT code,
* size of tire--\"205/55 R16 V\",
* Brand--\"Continental\",
* Type--\"ContiEcoContact\",
* others. Other additional tire parts include the rim protector, bead wire, bead contour and filler, polyester casing, steel belts, cap ply and inner liner. Each part fulfills a specific function, has a specific shape and is made of specific material. From the point of view of quality evaluation and pattern of the surface, mainly the outer surfaces are interesting--tread (significant pattern defined by adhesion to the ground surface), sidewall (pattern defined by other driving characteristics, aesthetic design requirements and legislative requirements, e.g., tire data) and inner liner (determined by production technology and mechanical properties of the tire) or rim protector (surface smoothness due to tightness). All of these surfaces can be inspected; however, from the point of view of visual inspection, the sidewall and tread are the most important. Every difference in pattern on that surface can be highlighted and then the inspection system supposes defects with a high level of confidence [23]. Inspections of sidewall defects on a tire is a perspective for evaluating the system, since specific and different patterns occur. Thus, a texture has to be classified as a correct pattern. Every defect could be appearing on a tire, requiring them to be found by the inspection system. Correct patterns relative to defects are possible to determine. This assumption is based on [16; 17; 18] in which is it possible to find defects in colorized images with high variance of colours [24; 25]. Inspection of defects on a tire, where the essential colour is black, which are displayed on captured images from a vision system like shades of grey, impose specific conditions. This characteristic requires a specific set up based on an appropriate lighting system.