Comparison of three edge detection methods for image analysis of fragmented sandstones and bricks

The quantitative determination of fragment size is essential at various stages of mining. This can be achieved in different ways such as through sieving, by observation, and by analytical and empirical methods. A new method, digital image processing of photographs or video signals is introduced into this field. However, for the straightforward extension of the concept of image processing to the field it is necessary to determine the feasibility of this method initially at laboratory level. Moreover, it is also necessary to establish the accuracy and reliability of the method on rock fragments of irregular shapes. In this paper, the development of software to calculate the size of rock fragments using photographs is reported. Furthermore, the accuracy and reliability of the method is compared with manual measurements for calibration purpose. The work reveals that the suitability of the image processing method depends on the nature of projected surfaces of mixed and overlapping rock fragments in the case of muckpiles. Good accuracy is obtained in the case of isolated rock fragments.