1. A noninvasive physiological monitor comprising: a first input for receiving an output waveform from a detector responsive to light attenuated by body tissue, the output waveform including at least a first waveform corresponding to a first wavelength of light attenuated by body tissue and a second waveform corresponding to a second wavelength of light attenuated by the body tissue; and a signal processor configured to transform said first and second waveforms into spectral domain waveforms, the signal processor further configured to distinguish motion artifacts, classify portions of the spectral domain waveforms by at least matching a set of peaks in the spectral domain waveforms to one of a plurality of cases, and select spectral data from the spectral domain waveforms based on the classification and predetermined criteria, the signal processor further configured to determine a physiological indication of the patient based on the selected spectral data.