Novel systems and methods for performing treatment (e.g., coloration) of keratinous fibers are disclosed. The methods and systems utilize one or more of a dispensing device which is configured to provide customized composition for treating keratinous fibers (e.g., a coloring composition), optionally formed from tablets; an optical reader, for obtaining sufficient characteristics of the keratinous fibers to make a realistic prediction of the outcome of a treatment (e.g., coloring treatment); a computational units for predicting an outcome of a treatment, optionally being interfaced with the dispensing device and for selecting a customized treatment; and tablet formulations which are useful in preparing customized composition for treating keratinous fibers. Further disclosed are rapidly disintegrating tablets for use in the preparation of compositions for treating keratinous fibers.