diff --git a/atomai/utils/preproc.py b/atomai/utils/preproc.py
index 85782cd..f9212ee 100644
--- a/atomai/utils/preproc.py
+++ b/atomai/utils/preproc.py
@@ -757,7 +757,7 @@ def torch_format_image(image_data: np.ndarray,
     else:
         pass
     if norm:
-        image_data = (image_data - image_data.min()) / image_data.ptp()
+        image_data = (image_data - image_data.min()) / np.ptp(image_data)#image_data.ptp()
     image_data = torch.from_numpy(image_data).float()
     return image_data
 
@@ -786,7 +786,7 @@ def torch_format_spectra(spectra: np.ndarray,
     else:
         pass
     if norm:
-        spectra = (spectra - spectra.min()) / spectra.ptp()
+        spectra = (spectra - spectra.min()) / np.ptp(spectra)#spectra.ptp()
     spectra = torch.from_numpy(spectra).float()
     return spectra