From 686814f2265fc287985c8c27d0b59ac4e7a34ede Mon Sep 17 00:00:00 2001
From: stscicrawford <scrawford@stsci.edu>
Date: Sun, 28 Jul 2019 12:30:46 -0400
Subject: [PATCH 1/2] added warning to transform_image that it does not apply
 to WCS

---
 CHANGES.rst                   |  3 +++
 ccdproc/core.py               | 13 ++++++++++---
 ccdproc/tests/test_ccdproc.py |  9 +++++++++
 3 files changed, 22 insertions(+), 3 deletions(-)

diff --git a/CHANGES.rst b/CHANGES.rst
index 864425a2..61d33318 100644
--- a/CHANGES.rst
+++ b/CHANGES.rst
@@ -19,6 +19,9 @@ Other Changes and Additions
 
 - Added support for .bz2, .Z and .zip file formats in ``ImageFileCollection``.
 
+- Added warning that ``transform_image`` does not apply the transformation to the WCS [#684]
+
+
 Bug Fixes
 ^^^^^^^^^
 - Function ``median_combine`` now correctly calculates the uncertainty for
diff --git a/ccdproc/core.py b/ccdproc/core.py
index 13da2d84..e95b9a86 100644
--- a/ccdproc/core.py
+++ b/ccdproc/core.py
@@ -2,10 +2,13 @@
 
 """This module implements the base CCDPROC functions"""
 
+import math
 import numbers
+import logging
 
 import numpy as np
-import math
+from scipy import ndimage
+
 from astropy.units.quantity import Quantity
 from astropy import units as u
 from astropy.modeling import fitting
@@ -16,12 +19,12 @@
 from astropy.utils import deprecated
 import astropy  # To get the version.
 
-from scipy import ndimage
-
 from .utils.slices import slice_from_string
 from .log_meta import log_to_metadata
 from .extern.bitfield import bitfield_to_boolean_mask as _bitfield_to_boolean_mask
 
+logger = logging.getLogger(__name__)
+
 __all__ = ['background_deviation_box', 'background_deviation_filter',
            'ccd_process', 'cosmicray_median', 'cosmicray_lacosmic',
            'create_deviation', 'flat_correct', 'gain_correct', 'rebin',
@@ -853,6 +856,10 @@ def transform_image(ccd, transform_func, **kwargs):
         mask = transform_func(nccd.mask, **kwargs)
         nccd.mask = mask > 0
 
+    if nccd.wcs is not None:
+        warn = 'WCS information may be incorrect as no transformation was applied to it'
+        logging.warning(warn)
+
     return nccd
 
 
diff --git a/ccdproc/tests/test_ccdproc.py b/ccdproc/tests/test_ccdproc.py
index f61c2be5..bfe96bdd 100644
--- a/ccdproc/tests/test_ccdproc.py
+++ b/ccdproc/tests/test_ccdproc.py
@@ -573,6 +573,15 @@ def test_transform_isfunc(ccd_data):
     with pytest.raises(TypeError):
         transform_image(ccd_data, 1)
 
+#test warning is issue if WCS information is available
+def test_catch_transform_wcs_warning(ccd_data):
+
+    def tran(arr):
+        return 10 * arr
+
+    with catch_warnings() as w:
+         tran = transform_image(ccd_data, tran)
+
 
 @pytest.mark.parametrize('mask_data, uncertainty', [
                          (False, False),

From fc8f932d4e1c402d4ac472df41ab672cb8fda348 Mon Sep 17 00:00:00 2001
From: Steve Crawford <crawfordsm@gmail.com>
Date: Sun, 28 Jul 2019 14:50:32 -0400
Subject: [PATCH 2/2] Update test_ccdproc.py

fix indentation
---
 ccdproc/tests/test_ccdproc.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/ccdproc/tests/test_ccdproc.py b/ccdproc/tests/test_ccdproc.py
index bfe96bdd..c8f67214 100644
--- a/ccdproc/tests/test_ccdproc.py
+++ b/ccdproc/tests/test_ccdproc.py
@@ -580,7 +580,7 @@ def tran(arr):
         return 10 * arr
 
     with catch_warnings() as w:
-         tran = transform_image(ccd_data, tran)
+        tran = transform_image(ccd_data, tran)
 
 
 @pytest.mark.parametrize('mask_data, uncertainty', [