Systems for custom coloration

A device for preparing a customized composition for treating keratinous fibers, the composition comprising a plurality of solid formulations in a tablet form, the device comprising

• a plurality of containers, each container having an outlet suitable for dispensing a tablet;
• and a dispensing unit for dispensing a pre-determined amount of tablets, said containers and said dispensing unit being attachable to one another.

A device for optical measurement of keratinous fibers, comprising:

• an illumination unit for illuminating keratinous fibers;
• a measuring unit comprising at least one sensor for optically measuring said keratinous fibers during illumination by said illumination unit;
• wherein the sensor and a beam from the illumination unit respectively subtend a light diffusion angle at the keratinous fibers being measured, thereby to ensure that said sensor principally measures light of said illumination beam that is diffused or scattered by said keratinous fibers.