A method for controlling a transformation process in which the conversion of charge materials to a product takes place along a transformation interface from the crystal and/or grain and/or phase and/or pore surface into the charge material, wherein one or more chemical elements in the charge materials is released and/or incorporated and/or rearranged and wherein the conversion of the charge materials takes place along advancing transformation interfaces. The charge materials are identified on the basis of at least one optical, in particular microscopic, analysis with respect to their phases and/or phase components and/or their phase morphology, structure, texture and/or their chemical composition. On the basis of these variables, reference functions for the charge materials, which describe the conversion of the charge materials in the process, are assigned and used for establishing the process parameters of the transformation process.