Soil cracking has been studied for many decades; however, it still deserves further investigation. This paper describes a new testing device that uses image processing to perform simultaneous and continuous quantification of the vertical strain and radial strain, crack area, and water content of a soil specimen subjected to suction cycles imposed by the vapour equilibrium method. An image processing method was designed to determine the crack area and the soil radial strain separately. The evolution of each measured parameter over time in a clayey soil specimen subjected to 3 suction cycles is presented and discussed. The first suction cycle has the greatest impact on the crack area, the mass water content, the vertical strains and the radial strains. Hysteresis loops were observed for crack area and radial strain evolution.