Abstract: A system and method for color measurements or other spectral measurements of a material are provided. An illuminating device generates light for illuminating a sample of material. A detector detects light that has interacted with the sample and provides a measurement of the light that has interacted with the sample. A controller adjusts a duty cycle of the illuminating device to control the illumination of the sample. The measurement could be used by an analyzer to determine a spectral characteristic of the sample (such as a color of the sample). The determination of the spectral characteristic could be done without using any measurement of light that has not interacted with the sample. One or multiple light emitting diodes (LEDs) could be used to illuminate the sample, and the duty cycle of individual LEDs or groups of LEDs could be adjusted.

Abstract: A projection is associated with a first signal and a second signal. The second signal includes a first portion associated with the first signal and a second portion not associated with the first signal. The projection at least substantially separates the first portion of the second signal from the second portion of the second signal. One or more parameters of a model are identified using at least a portion of the projection. The model associates the first signal and the first portion of the second signal.