Systems and methods for measuring spectra and other optical characteristics such as colors, translucence, gloss, and other characteristics of objects and materials such as skin. Instruments and methods for measuring spectra and other optical characteristics of skin or other translucent or opaque objects utilize an abridged spectrophotometer and improved calibration/normalization methods. Improved linearization methods also are provided, as are improved classifier-based algorithms. User control is provided via a graphical user interface. Product or product formulations to match the measured skin or other object or to transform the skin or other object are provided to lighten, darken, make more uniform and the like.