Apparatus and methods are provided to control a device, such as a light emitting dermatologic or cosmetic treatment device, and ensure that the device is in contact with skin while also determining the pigmentation level of skin. One or more light sources contact the skin and one or more detectors measure spectral remission from the skin. The obtained remission measurements are compared with known skin spectral remission values, and calibration allows measurements of absolute remission to be converted to fractional remission values. Skin pigmentation levels are compared to known base-line levels to determine and control appropriate treatment parameters. A temperature sensor allows correction for temperature variations. The apparatus may or may not be incorporated into the treatment device.