The interpretation of X-ray computed microtomography images of rocks as an application of volume image processing and analysis

摘要

X-ray computed microtomography (CMT) is a non-destructive method of investigating internal structure of examined objects. During the reconstruction of CMT measurement data, large volume images are generated. Therefore, the image processing and analysis are very important steps in CMT data interpretation. The first step in analyzing the rocks is image segmentation. The differences in density are shown on the reconstructed image as the differences in gray level of voxel, so the proper threshold operation must be carried out. As a result, the different mineral phases and pores can be separated at the image. Segmented and binarized image is the base for further operations which depend on the aim of research. Numerical analysis gives information about the pore shapes and volumes as well as connections between pores in the pore network. The image may also be used in numerical physics simulation (for example fluid flow simulation), but before that it has to be filtered and resampled. These operations are very important, because if performed poorly, they may lead to rupture the pore network. The aim of this paper is to present authors’ methodology of CMT image processing and analysis and to show problems occurring during these processes. The image processing of two rock samples CMT image will be presented.