TString dir = gROOT->GetTutorialDir(); auto c = new TCanvas("c1", "FITS tutorial #1", 800, 700); c->Divide(2, 3); for (auto i : ROOT::TSeqI(1, 6)) { TFITSHDU hdu(dir + "/fitsio/sample3.fits", i); TImage* im = (TImage *)hdu.ReadAsImage(0); c->cd(i); im->Draw(); } gROOT->GetListOfCanvases()->Draw()