When assessing a mixing process, mixing quality is a characteristic parameter. To determine the optimum mixing time, it is necessary to measure the mixing efficiency as a function of mixing time. Mixing efficiency is determined by a sufficient number of sample analyses after certain mixing times. The novel method of image analysis allows to rapidly determine the optimum mixing time without sampling and complex sample analysis being required. In this study the model products have different particle sizes and colors to see a difference between them in the image analysis program. Analyzing a real mixture to find chemical substitutes for all particle components is impossible. The study can help the plant engineer to mark a component of interest for finding the optimum point of stationary equilibrium. In this paper the theory for sampling and comparing multi-component mixtures by image analysis to determine the mixing efficiency will be also described and discussed. (c) 2007 Elsevier B.V. All rights reserved.