The experimental data of the spectral-reflectance factor are considered as dependent on the instrument-spectral-bandwidth function in order to perform their deconvolution and to compute the tristimulus values. The deconvolution is performed by local-power expansion. In the case that the spectral-bandpass dependence regards only the spectral transmittance of the monochromator, the goodness of this technique is evaluated by simulation (1325 reflectance factors of the Munsell samples are considered as trial functions) and compared with other usual techniques: Stearns and Stearns method for bandpass error, ASTMweighting function interpolation, and Venable-ASTM weighting function. The zero order of the deconvoluted spectral-reflectance factor can be related to the Stearns and Stearns method for bandpass error. With respect to any other technique, the second-order deconvolution, for the CIE standard illuminants, gives color differences lower by a factor 0.1 or more for a bandpass ⌬ ϭ 10 nm, color differences lower by a factor 0.3 or more for a bandpass ⌬ ϭ 20 nm and, for the CIE fluorescent illuminants, color differences generally lower.