#include <TSpectrum2.h>

void Background_gamma256()
{
   Int_t i, j;
   const Int_t nbinsx = 64;
   const Int_t nbinsy = 64;
   Double_t xmin = 0;
   Double_t xmax = (Double_t)nbinsx;
   Double_t ymin = 0;
   Double_t ymax = (Double_t)nbinsy;
   Double_t **source = new Double_t *[nbinsx];
   for (i = 0; i < nbinsx; i++)
      source[i] = new Double_t[nbinsy];
   TString dir = gROOT->GetTutorialDir();
   TString file = dir + "/legacy/spectrum/TSpectrum2.root";
   TFile *f = new TFile(file.Data());
   auto back = (TH2F *)f->Get("back2");
   gStyle->SetOptStat(0);
   auto *s = new TSpectrum2();
   for (i = 0; i < nbinsx; i++) {
      for (j = 0; j < nbinsy; j++) {
         source[i][j] = back->GetBinContent(i + 1, j + 1);
      }
   }
   s->Background(source, nbinsx, nbinsy, 8, 8, TSpectrum2::kBackIncreasingWindow, TSpectrum2::kBackSuccessiveFiltering);
   for (i = 0; i < nbinsx; i++) {
      for (j = 0; j < nbinsy; j++)
         back->SetBinContent(i + 1, j + 1, source[i][j]);
   }
   back->Draw("SURF2");
}