The characterisation of the pore texture of macroporous materials is still laborious. In this contribution, it is shown that the methods of digital image processing can also be helpful to obtain useful data of a macropore system. In order to characterise it, images representing the macropore system must be available for the computer. Taking digitised microphotographs of prepared specimens, characteristic data such as the accessible porosity, the mean pore diameter, the mean pore connectivity as well as the tortuosity factor can be determined. The proposed methods can also be used if the question arises what influence pore filling processes have on the accessibility of the pore space as well as on the tortuosity of the porous systems. Two pore filling processes, the film formation as well as the coke formation process taking place at random in the pore space are simulated. The results obtained show that the coke formation process leads to pore blocking much earlier than the film formation. In addition, computer algorithms using the images were carried out to determine the influence of pore narrowing on the tortuosity factor.