update based on comments

Signed-off-by: Wenqi Li <wenqil@nvidia.com>

monai/data/image_writer.py

@@ -373,11 +373,11 @@ class ITKWriter(ImageWriter):
     output_dtype: DtypeLike = None
     channel_dim: int | None
 
-    def __init__(self, output_dtype: DtypeLike = np.float32, affine_lps_to_ras: bool | None = None, **kwargs):
+    def __init__(self, output_dtype: DtypeLike = np.float32, affine_lps_to_ras: bool | None = True, **kwargs):
         """
         Args:
             output_dtype: output data type.
-            affine_lps_to_ras: whether to convert the affine matrix from "LPS" to "RAS". Defaults to ``None``.
+            affine_lps_to_ras: whether to convert the affine matrix from "LPS" to "RAS". Defaults to ``True``.
                 Set to ``True`` to be consistent with ``NibabelWriter``,
                 otherwise the affine matrix is assumed already in the ITK convention.
             kwargs: keyword arguments passed to ``ImageWriter``.
@@ -478,7 +478,7 @@ def create_backend_obj(
         channel_dim: int | None = 0,
         affine: NdarrayOrTensor | None = None,
         dtype: DtypeLike = np.float32,
-        affine_lps_to_ras: bool | None = None,
+        affine_lps_to_ras: bool | None = True,
         **kwargs,
     ):
         """
@@ -489,7 +489,7 @@ def create_backend_obj(
             channel_dim: channel dimension of the data array. This is used to create a Vector Image if it is not ``None``.
             affine: affine matrix of the data array. This is used to compute `spacing`, `direction` and `origin`.
             dtype: output data type.
-            affine_lps_to_ras: whether to convert the affine matrix from "LPS" to "RAS". Defaults to ``None``.
+            affine_lps_to_ras: whether to convert the affine matrix from "LPS" to "RAS". Defaults to ``True``.
                 Set to ``True`` to be consistent with ``NibabelWriter``,
                 otherwise the affine matrix is assumed already in the ITK convention.
             kwargs: keyword arguments. Current `itk.GetImageFromArray` will read ``ttype`` from this dictionary.