Some urgent problems in the study of secondary images are discussed. A particular emphasis is made on the systems approach. Correspondingly basic concepts and classifications of secondary images are critically considered. The necessity to look for common mechanisms of generation of particular types of imagery phenomena, and to work out a multidimensional classification of properties of secondary images is underlined. Special attention is given to methods of studying secondary images and of measuring their particular dimensions. The problem of individual peculiarities of secondary images is also dealt with, and some possible ways of its further study are suggested.