diff --git a/pycrostates/cluster/_base.py b/pycrostates/cluster/_base.py
index a010a285..4dbad41b 100644
--- a/pycrostates/cluster/_base.py
+++ b/pycrostates/cluster/_base.py
@@ -953,22 +953,15 @@ def _segment(
         half_window_size: int,
     ) -> NDArray[int]:
         """Create segmentation. Must operate on a copy of states."""
-        data -= np.mean(data, axis=0)
-        std = np.std(data, axis=0)
-        std[std == 0] = 1  # std == 0 -> null map
-        data /= std
-
-        states -= np.mean(states, axis=1)[:, np.newaxis]
-        states /= np.std(states, axis=1)[:, np.newaxis]
-
-        _correlation(data, states, ignore_polarity=ignore_polarity)
-        labels = np.argmax(np.abs(np.dot(states, data)), axis=0)
+        corr = _correlation(states, data, ignore_polarity=ignore_polarity)[:len(states), :]
+        if ignore_polarity:
+            corr = np.abs(corr)
+        labels = np.argmax(corr, axis=0)
 
         if factor != 0:
             labels = _BaseCluster._smooth_segmentation(
                 data, states, labels, ignore_polarity, factor, tol, half_window_size
             )
-
         return labels
 
     @staticmethod
@@ -1064,12 +1057,12 @@ def _reject_short_segments(
                         _correlation(
                             data[:, left - 1].reshape(-1, 1),
                             data[:, left].reshape(-1, 1),
-                            ignore_polarity=True,
+                            ignore_polarity=ignore_polarity,
                         )[0, 0]
                     )
                     right_corr = np.abs(
                         _correlation(
-                            data[:, right], data[:, right + 1], ignore_polarity=True
+                            data[:, right], data[:, right + 1], ignore_polarity=ignore_polarity
                         )[0, 0]
                     )
 
diff --git a/pycrostates/segmentation/_base.py b/pycrostates/segmentation/_base.py
index f1825613..95fd91d2 100644
--- a/pycrostates/segmentation/_base.py
+++ b/pycrostates/segmentation/_base.py
@@ -155,7 +155,7 @@ def compute_parameters(self, norm_gfp: bool = True, return_dist: bool = False):
             # create a 1D view of the labels array
             labels = labels.reshape(-1)
 
-        gfp = np.std(data, axis=0)
+        gfp = np.std(data, axis=0) #TODO: change gfp
         if norm_gfp:
             labeled = np.argwhere(labels != -1)  # ignore unlabeled segments
             gfp /= np.linalg.norm(gfp[labeled])  # normalize
@@ -171,9 +171,9 @@ def compute_parameters(self, norm_gfp: bool = True, return_dist: bool = False):
                 labeled_gfp = gfp[arg_where][:, 0]
                 state_array = np.array([state] * len(arg_where)).transpose()
 
-                dist_corr = _correlation(state_array, labeled_tp, ignore_polarity=True)
+                dist_corr = _correlation(state_array, labeled_tp, ignore_polarity=True) #TODO: ignore_polarity
                 params[f"{state_name}_mean_corr"] = np.mean(np.abs(dist_corr))
-                dist_gev = (labeled_gfp * dist_corr) ** 2 / np.sum(gfp**2)
+                dist_gev = (labeled_gfp * dist_corr) ** 2 / np.sum(gfp**2) #TODO: gev
                 params[f"{state_name}_gev"] = np.sum(dist_gev)
 
                 s_segments = np.array([len(group) for s_, group in segments if s_ == s])