Research Of Color Difference And Dimension Measurement Of Ceramic Tile Based On CCD

Ceramic tile is a kind of commonly used building material.Due to the technology and some other reasons, the color difference inspection and dimension measurement of ceramic tile is still done by human inspectors at present. Therefore developing an automated color difference inspection algorithm and dimension measurement algorithm is of great importance, which can effectively resolve the problems brought by manual activity, and can help to improve the full automation in the tile industry.Based on CCD cameras system, technique of image processing, theories and methods of the color difference inspection and dimension measurement of tiles are studied in this dissertation. Firstly, the possibility of system's fulfillment from the view of hardware are analyzed in this dissertation. The properties of illumination devices, CCD cameras and frame grabbers and how to choose them are discussed;Secondly, several image processing method are compared in the examination, such as median filtering method,edge extraction method,and choose them to process image;Thirdly , minimum distance method based on regular color-space and color histogram comparison method based on HSV color-space are proposed. In the discussion of minimum distance method, a general small color difference computation method based on order set and a basic color abstraction method–histogram segmentation are analyzed. How to get characteristic vector regarded as the color feature of image and compare characteristic vector's histogram are discussed in the method of color histogram comparison. Finally, in the dimension measurement aspect , standard measuring gauge is used to demarcate the system.The least square method is used to analyze and fit edge points to draw the whole edge information.The possibility of the two methods of color difference inspection are analyzed. The method of color histogram intersection based on HSV is not useful in color difference inspection and the minimum distance method based on regular color-space is feasible. Experiment of dimension measurement show that the accuracy and stability of method can satisfy the practical requirements. Finally, the further the whole work in this research direction is given out after, and the measures of improvement are proposed.