fix: reverted mask generation to match matlab art

Author: satra

nipype/algorithms/rapidart.py

@@ -376,9 +376,7 @@ def _detect_outliers_core(self, imgfile, motionfile, runidx, cwd=None):
                     # Use an SPM like approach
                     mask_tmp = vol > \
                                (_nanmean(vol) / self.inputs.global_threshold)
-                    g_vol = np.nansum(vol * mask_tmp)/np.nansum(mask_tmp)
-                    mask = mask * \
-                        (vol > g_vol)
+                    mask = mask * mask_tmp
                 for t0 in range(timepoints):
                     vol = data[:, :, :, t0]
                     g[t0] = _nanmean(vol[mask])