Electron microscopy
Top-Hat Filter for EELS
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Top-hat filter had been suggested as a digital filter for EELS to detect and identify weak core-edges, and supprese steep-sloped background to get a linear baseline in EELS. [1] As shown in Figure 1002, in the EELS spectrum, assuming the filter width is w, then the integrated intensities (signals) of the three adjoining areas are given by Sx-1, Sx, and Sx+1. Therefore, the filtered value in the window xi is given by,
          F(xi) = 2*Sxi - (Sxi-w + Sxi+w) ------------------------------- [1002]

Note that smoothing effect becomes stronger with the increase of the filter width w. [1]

A filter script is: (script file)








[1] Jun Hosoi, Tetsuo Oikawa, Masao Inoue and Yasushi Kokubo, J. Electron Microsc, Vol. 34, No. 1, 1-7, 1985.