Smart optical sensor system for the real time detection of decorations defects of traditional ceramic tiles

Project Information

Grant agreement ID: BRST975137

Project closed

Start date 1 December 1997

End date 30 November 1999

Funded under

• Specific research and technological development programme in the field of industrial and materials technologies, 1994-1998

Total cost No data

EU contribution No data

Coordinated by

North Electronic Systems SpA
Italy

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Exploitable results

Complete system for the inspection of the tiles during the printing/after the firing phases for the detection of the decoration defects.

The automatic control system for the detection of decoration defects of ceramic tiles is based on the application and further development of a smart optical sensor. Two applications of the system have been developed based on the requirements of the tile manufacturers in the consortium: - Application A is addressed to the inspection of the tiles during the printing phases and it allows to detect forming and printing defects in the earlier tile production phases in order to increase the production share of high quality tiles. - Application B is designed to classify finished tiles by the colour tonality of the tile surface according to the human eye perception of colour. For both the applications the equipment and the software developed within the STILE Project has been designed to be controlled by low cost computers. The project result consists of a prototype system for tile defect detection or tile colour classification, equipped with a smart camera, a spectrograph, and a lighting system designed to this purpose.

Algorithms and image processing techniques for image analysis, defect detection, colour tone analysis, and tile sorting

This result consists of the specific software algorithms for defect detection and colour classification both developed for the Smart Camera coupled to the Spectrograph for PC platforms. The developed algorithms comprise procedures for defect detection on the surface of decorated ceramic tiles A) after printing and B) before firing. After printing several defect typologies or machine failures can be detected by using a 'black and white' image processing approach. For example, the defect created by a missing printing of part of the tile can be detected by comparison with a target reference pattern. After printing the detection of differences in colour tonality or, more generally, colour defects on the tile surface can be detected using spectral imaging and colour image analysis approaches.

Integration of sensors and related optical components for the colour evaluation

This result consists of the updated sensor, the related optical components (basically the smart camera and the spectrograph), and the illumination system, integrated under the project to account for the fast and accurate evaluation of colour tonality variation on relative wide surfaces. These components are used in an automatic system for detection of decoration defects of traditional ceramic tiles or tile colour classification based on low cost computers. The characteristics and the settings of the camera and of the spectrograph, together with the illumination system, are particularly suitable to be applied in fast industrial processes.