Although pore diffusion processes play an important role in many practical applications, the determination of the value of a given diffusion coefficient is still laborious. This is due to the fact that diffusion in porous media is influenced by molecular mechanisms as well as by the pore texture. In our contribution we suggest a method for determining the effective Knudsen diffusion coefficient that accounts for the pore texture with the help of digital image processing. In order to achieve that, a microphotograph taken from a slice of a given porous support material is taken and loaded into a computer. As a result of such a procedure we have a stored two-dimensional copy of the pore space, which can be used to simulate the diffusional transport. Furthermore, this picture can be used to determine some characteristics of the pore texture such as the connectivity. It is shown that the method for determining the effective Knudsen diffusion coefficient can indeed give realistic values.