A new taxonomy of color-related elements in art therapy assessment is defined, which consists of seven basic color-related, three explicitly color-related, six implicitly color-related, and three pattern color-related elements. Several computer systems were already developed for the evaluation of these 19 elements, except for the 3 elements in the FEATS (Formal Elements Art Therapy Scale): the prominence of color, the details of the objects and environment, and the space. We developed a computer system to evaluate these three elements by applying regression models. The system was verified through 45 PPAT (a Person Picking an Apple from a Tree) sample drawings in the FEATS rating manual. Integrating the system with several existing computer systems yields the Computer_Color-Related Elements Art Therapy Evaluation System (C_CREATES), which can be a useful tool that can automatically provide art therapists with an objective, detailed and quantitative evaluation of color-related elements and reduce the time and effort involved in evaluating the various color-related elements in quite a large number of drawings.