Denoising Step-by-Step. Demonstration of the contribution of each step of the analysis for pattern extraction on Chr.1 for the glioma data-set. A) Average profile of expression for Chr 1 for all the 27 tumour cases. B) Main pattern of expression (81% of total variability) detected by SVD. C) Effect of de-noising on the SVD pattern. D) Additional noise removal by inter-probe distance penalization.