QC_HISTO performs quality control using histogram and entropy analysis
R = qc_histo(filename [,CHAN]);
plota(R); displays the result as in [1]
References:
[1] A. Schl�l, B. Kemp, T. Penzel, D. Kunz, S.-L. Himanen, A. V�ri, G. Dorffner, G. Pfurtscheller.
Quality Control of polysomnographic Sleep Data by Histogram and Entropy Analysis.
Clin. Neurophysiol. 1999, Dec; 110(12): 2165 - 2170.
http://dx.doi.org/10.1016/S1388-2457(99)00172-8