An automatic image analysis of coke texture Original Research Article

A method for automatic image analysis of coke texture has been developed. The method uses an optical polarizing reflecting light microscope, with automatic sample movement. A series of images sized 405 × 270 mm is captured using a CCD video camera. These images are subdivided into six squares at 135 × 135 mm each. For each of these squares an image displaying the contours of the optical domains is made. This contour image is based on either thresholding or a grey level gradient. The structure is then characterized by the mean density and preferred direction of the contours in these square images. The method thus yields two values: A coarseness index, and a fibre index. These values do not require any classification of the texture into a finite number of texture classes. Commercial anode cokes as well as needle and pitch coke have been characterized. Reproducible results were obtained after 100 images (600 squares) were analysed. The differences between the commercial anode cokes are small but reproducible, while the pitch and needle coke deviate strongly.