Title | Automated estimation of white Gaussian noise level in a spectrum with or without spike noise using a spectral shifting technique |
Publication Type | Journal Article |
Year of Publication | 2006 |
Authors | Schulze, H. G., M. M. L. Yu, C. J. Addison, M. W. Blades, and R. F. B. Turner |
Journal | Applied Spectroscopy |
Volume | 60 |
Pagination | 820–825 |
ISSN | 0003-7028 |
Abstract | Various tasks, for example, the determination of signal-to-noise ratios, require the estimation of noise levels in a spectrum. This is generally accomplished by calculating the standard deviation of manually chosen points in a region of the spectrum that has a flat baseline and is otherwise devoid of artifacts and signal peaks. However, an automated procedure has the advantage of being faster and operator-independent. In principle, automated noise estimation in a single spectrum can be carried out by taking that spectrum, shifting a copy thereof by one channel, and subtracting the shifted spectrum from the original spectrum. This leads to an addition of independent noise and a reduction of slowly varying features such as baselines and signal peaks; hence, noise can be more readily determined from the difference spectrum. We demonstrate this technique and a spike-discrimination variant on white Gaussian noise, in the presence and absence of spike noise, and show that highly accurate results can be obtained on a series of simulated Raman spectra and consistent results obtained on real-world Raman spectra. Furthermore, the method can be easily adapted to accommodate heteroscedastic noise. |