a spectral image processing method is capable of reducing noise while maintaining necessary information . the spectral image processing method performs processing on a spectral image of a specimen , including a step of normalizing spectra of respective pixels constituting the spectral image such that their brightness levels become equal , a step of smoothing the normalized spectra in spatial directions of the respective pixels , and a step of denormalization of multiplying spectra of the respective pixels obtained by the smoothing by either one of brightness levels of the pixels corresponding the spectra and values corresponding to the brightness levels . consequently , the noise can be reduced while information on brightness distribution on the image is maintained .