diff --git a/src/eynollah/ocrd_cli_binarization.py b/src/eynollah/ocrd_cli_binarization.py
index 848bbac..e5fa740 100644
--- a/src/eynollah/ocrd_cli_binarization.py
+++ b/src/eynollah/ocrd_cli_binarization.py
@@ -10,16 +10,7 @@ from ocrd_models.ocrd_page import OcrdPage, AlternativeImageType
 from ocrd.decorators import ocrd_cli_options, ocrd_cli_wrap_processor
 
 from .sbb_binarize import SbbBinarizer
-
-
-def cv2pil(img):
-    return Image.fromarray(img.astype('uint8'))
-
-def pil2cv(img):
-    # from ocrd/workspace.py
-    color_conversion = cv2.COLOR_GRAY2BGR if img.mode in ('1', 'L') else  cv2.COLOR_RGB2BGR
-    pil_as_np_array = np.array(img).astype('uint8') if img.mode == '1' else np.array(img)
-    return cv2.cvtColor(pil_as_np_array, color_conversion)
+from .utils.pil_cv2 import cv2pil, pil2cv
 
 class SbbBinarizeProcessor(Processor):
     # already employs GPU (without singleton process atm)
diff --git a/src/eynollah/utils/pil_cv2.py b/src/eynollah/utils/pil_cv2.py
index 9f6913e..36228a7 100644
--- a/src/eynollah/utils/pil_cv2.py
+++ b/src/eynollah/utils/pil_cv2.py
@@ -7,12 +7,18 @@ from cv2 import COLOR_GRAY2BGR, COLOR_RGB2BGR, COLOR_BGR2RGB, cvtColor, imread
 # from sbb_binarization
 
 def cv2pil(img):
-    return Image.fromarray(np.array(cvtColor(img, COLOR_BGR2RGB)))
+    # reduce depth because cvtColor is limited
+    return Image.fromarray(np.array(cvtColor(img.astype(np.uint8), COLOR_BGR2RGB)))
 
 def pil2cv(img):
     # from ocrd/workspace.py
-    color_conversion = COLOR_GRAY2BGR if img.mode in ('1', 'L') else  COLOR_RGB2BGR
+    color_conversion = COLOR_GRAY2BGR if img.mode in ('1', 'L', 'LA') else  COLOR_RGB2BGR
     pil_as_np_array = np.array(img).astype('uint8') if img.mode == '1' else np.array(img)
+    # cvtColor cannot handle alpha
+    if pil_as_np_array.shape[-1] == 2:
+        pil_as_np_array = pil_as_np_array[:,:,0]
+    elif pil_as_np_array.shape[-1] == 4:
+        pil_as_np_array = pil_as_np_array[:,:,:3]
     return cvtColor(pil_as_np_array, color_conversion)
 
 def check_dpi(img):