diff --git a/stereo/algorithm/cell_correction_fast_by_mask.py b/stereo/algorithm/cell_correction_fast_by_mask.py
index 3379eb55..4313e756 100644
--- a/stereo/algorithm/cell_correction_fast_by_mask.py
+++ b/stereo/algorithm/cell_correction_fast_by_mask.py
@@ -205,7 +205,7 @@ def array_to_block(
     bpc = (width - overlap) // (col_block_size - overlap)  # blocks per column
     if ((height - overlap) % (row_block_size - overlap)) > 0:
         bpr += 1
-    if ((width - overlap) // (col_block_size - overlap)) > 0:
+    if ((width - overlap) % (col_block_size - overlap)) > 0:
         bpc += 1
     if n_split_data_jobs in (0, 1):
         block_list = [create_edm_labels(block) for block in
@@ -230,7 +230,9 @@ def merge_to_mask(final_result, bpr, bpc, mask, start, end, overlap=MASK_BLOCK_O
     for rr in range(bpr):
         row_img_list = []
         for cc in range(bpc):
-            if cc == 0:
+            if bpc == 1:
+                img = final_result[rr * bpc]
+            elif cc == 0:
                 img = final_result[rr * bpc][:, :-half_step]
             elif cc == bpc - 1:
                 img = final_result[rr * bpc + cc][:, half_step:]
@@ -239,7 +241,9 @@ def merge_to_mask(final_result, bpr, bpc, mask, start, end, overlap=MASK_BLOCK_O
             row_img_list.append(img)
         row_img = np.concatenate(row_img_list, axis=1)
 
-        if rr == 0:
+        if bpr == 1:
+            img = row_img
+        elif rr == 0:
             img = row_img[:-half_step]
         elif rr == bpr - 1:
             img = row_img[half_step:]
@@ -252,6 +256,22 @@ def merge_to_mask(final_result, bpr, bpc, mask, start, end, overlap=MASK_BLOCK_O
 
     return mask
 
+# @log_consumed_time
+# def merge_to_mask(final_result, bpr, bpc, mask, start, end, overlap=MASK_BLOCK_OVERLAP_DEFAULT):
+#     full_img_shape = (end[0] - start[0], end[1] - start[1])
+#     full_img = np.zeros(full_img_shape, dtype=mask.dtype)
+#     for rr in range(bpr):
+#         for cc in range(bpc):
+#             row_start = rr * (MASK_ROW_BLOCK_SIZE_DEFAULT - overlap)
+#             col_start = cc * (MASK_COL_BLOCK_SIZE_DEFAULT - overlap)
+#             row_end = min(row_start + MASK_ROW_BLOCK_SIZE_DEFAULT, full_img_shape[0])
+#             col_end = min(col_start + MASK_COL_BLOCK_SIZE_DEFAULT, full_img_shape[1])
+#             full_img[row_start:row_end, col_start:col_end] = final_result[rr * bpc + cc]
+
+#     mask[start[0]:end[0], start[1]:end[1]] = full_img
+
+#     return mask
+
 
 @log_consumed_time
 def est_para(mask):