astropy · astrofrog · Oct 30, 2023 · Oct 30, 2023 · Oct 30, 2023
diff --git a/CHANGES.md b/CHANGES.md
@@ -131,23 +131,23 @@
 ## 0.9 - 2022-09-02
 
 - Drop support for Python 3.7.
-- 
+-
 - Infrastructure and packaging updates.
-- 
+-
 - Made many improvements, bug fixes, and significant speed-ups for the adaptive
 - resampling algorithm, `reproject_adaptive`. These bug fixes may cause
 - changes to the reprojected images, which are typically negligible.
 - Improvements include the addition of a flux-conserving mode, support for a
 - Gaussian filter kernel, a menu of boundary-handling modes, and a
 - `center_jacobian` flag to trade speed for accuracy with rapidly-varying
 - transformations.
-- 
+-
 - Added a `roundtrip_coords` argument to `reproject_adaptive` and
 - `reproject_interp`. By default, all coordinate transformations are run in
 - both directions to handle some situations where they are ambiguous. This can
 - be disabled by setting `roundtrip_coords=False` which may offer a
 - significant speed increase.
-- 
+-
 
 ## 0.8 - 2021-08-11
 
@@ -156,34 +156,34 @@
 - possible to solve for the optimal WCS for a set of images that couldn't fit
 - into memory all at once, since the actual data aren't needed for optimal WCS
 - determination. [#242]
-- 
+-
 - Fix implementation of `hdu_weights` in `reproject_and_coadd`. [#249]
-- 
+-
 
 ## 0.7.1 - 2020-05-29
 
 - Fixed compatibility with Astropy 4.1. [#234]
-- 
+-
 - Updated minimum requirement for SciPy. [#236]
-- 
+-
 
 ## 0.7 - 2020-04-02
 
 - Made C extension in overlapArea.c thread-safe by removing global
 - variables. [#211]
-- 
+-
 - Made it possible to control whether to output debugging information
 - from overlapArea.c by setting DEBUG_OVERLAP_AREA=1 at build-time. [#211]
-- 
+-
 - Fix compatibility with astropy v4.0.1. [#227]
-- 
+-
 - Disable parallelization by default in `reproject_exact` - this can be
 - enabled with `parallel=True`. [#227]
-- 
+-
 - Fixed a bug with `reproject_exact` with `parallel=False` and
 - `return_footprint=False`, which caused the footprint to be returned
 - anyway. [#227]
-- 
+-
 - The infrastructure of the package has been updated in line with the
 - APE 17 roadmap (https://github.com/astropy/astropy-APEs/blob/main/APE17.rst).
 - The main changes are that the `python setup.py test` and
@@ -192,7 +192,7 @@
 - (https://tox.readthedocs.io) package and run `tox -e test` and
 - `tox -e build_docs`. It is also possible to run pytest and sphinx
 - directly. [#228]
-- 
+-
 
 ## 0.6 - 2019-11-01
 
@@ -201,20 +201,20 @@
 - `independent_celestial_slices=` argument to `reproject_interp` has
 - been deprecated since it is no longer needed, as transformations are
 - automatically done in the most efficient way possible. [#166]
-- 
+-
 - Include a warning for high resolution images with `reproject_exact`,
 - since if the pixels are <0.05", precision issues can occur. [#200]
-- 
+-
 - Added a new `reproject_and_coadd` function for doing mosaicking of
 - individual images, and added section in documentation about mosaicking.
 - [#186]
-- 
+-
 - Added a new reproject.adaptive sub-package that implements the DeForest
 - (2004) algorithm for reprojection. [#52]
-- 
+-
 - Fixed a bug that caused 'exact' reprojection results to have numerical
 - issues when doing identity transformations. [#190]
-- 
+-
 
 ## 0.5.1 - 2019-09-01
 
@@ -225,33 +225,33 @@
 
 - Improve parse_output_projection to make it so that the output projection
 - can be specified as a filename. [#150]
-- 
+-
 - Fixed a bug that caused HEALPix maps in RING order to not be correctly
 - interpreted. [#163]
-- 
+-
 - Make it possible to specify the output array for reprojection using the
 - `output_array=` keyword argument. [#115]
-- 
+-
 
 ## 0.4 - 2018-01-29
 
 - Refactored HEALPix reprojection code to use the astropy-healpix package
 - instead of healpy. [#139]
-- 
+-
 - Added the ability to specify an output array in `reproject_interp`, which
 - permits the use of memory-mapped arrays and therefore provides the capability
 - to handle data cubes much larger than memory [#115]
-- 
+-
 - Fix test 32-bit test failures. [#146]
-- 
+-
 - Fix an issue with reprojecting images where there are two solutions along
 - the line of sight by forcing round-tripping of coordinate conversions [#129]
-- 
+-
 - Explicitly define default HDU as 0 for normal reprojection and 1 for
 - HEALPix reprojection. [#119]
-- 
+-
 - Added a function to find the optimal WCS for a set of images. [#136, #137]
-- 
+-
 
 ## 0.3.2 - 2017-10-22
 
@@ -262,22 +262,22 @@
 ## 0.3.1 - 2016-07-07
 
 - Include missing license file in tarball.
-- 
+-
 - Updated documentation to remove warnings about early versions.
-- 
+-
 
 ## 0.3 - 2016-07-06
 
 - Allow users to pass a `field=` option to `reproject_from_healpix`
 - to access different fields in a HEALPIX file. [#86]
-- 
+-
 - Significant improvements to performance when the input data is a large
 - memory-mapped array. [#105]
-- 
+-
 - Significant refactoring of interpolating reprojection to improve support for
 - n-dimensional arrays, optionally including two celestial axes (in which
 - case the coordinate transformation is taken into account). [#96, #102]
-- 
+-
 
 ## 0.2 - 2015-10-29
 

diff --git a/reproject/healpix/high_level.py b/reproject/healpix/high_level.py
@@ -24,12 +24,14 @@ def reproject_from_healpix(
               second element is a `~astropy.coordinates.BaseCoordinateFrame`
               instance or a string alias for a coordinate frame.
 
-    output_projection : `~astropy.wcs.WCS` or `~astropy.io.fits.Header`
-        The output projection, which can be either a `~astropy.wcs.WCS`
-        or a `~astropy.io.fits.Header` instance.
+    output_projection : `~astropy.wcs.wcsapi.BaseLowLevelWCS` or `~astropy.wcs.wcsapi.BaseHighLevelWCS` or `~astropy.io.fits.Header`
+         The output projection, which can be either a
+         `~astropy.wcs.wcsapi.BaseLowLevelWCS`,
+         `~astropy.wcs.wcsapi.BaseHighLevelWCS`, or a `~astropy.io.fits.Header`
+         instance.
     shape_out : tuple, optional
-        If ``output_projection`` is a `~astropy.wcs.WCS` instance, the
-        shape of the output data should be specified separately.
+        If ``output_projection`` is a WCS instance, the shape of the output
+        data should be specified separately.
     hdu_in : int or str, optional
         If ``input_data`` is a FITS file, specifies the HDU to use.
         (the default HDU for HEALPIX data is 1, unlike with image files where
@@ -89,13 +91,18 @@ def reproject_to_healpix(
     input_data : object
         The input data to reproject. This can be:
 
-            * The name of a FITS file
+            * The name of a FITS file as a `str` or a `pathlib.Path` object
             * An `~astropy.io.fits.HDUList` object
-            * An image HDU object such as a `~astropy.io.fits.PrimaryHDU` or
-              `~astropy.io.fits.ImageHDU` instance
+            * An image HDU object such as a `~astropy.io.fits.PrimaryHDU`,
+              `~astropy.io.fits.ImageHDU`, or `~astropy.io.fits.CompImageHDU`
+              instance
             * A tuple where the first element is a `~numpy.ndarray` and the
-              second element is either a `~astropy.wcs.WCS` or a
+              second element is either a
+              `~astropy.wcs.wcsapi.BaseLowLevelWCS`,
+              `~astropy.wcs.wcsapi.BaseHighLevelWCS`, or a
               `~astropy.io.fits.Header` object
+            * An `~astropy.nddata.NDData` object from which the ``.data`` and
+              ``.wcs`` attributes will be used as the input data.
 
     coord_system_out : `~astropy.coordinates.BaseCoordinateFrame` or str
         The output coordinate system for the HEALPIX projection.

diff --git a/reproject/healpix/tests/test_healpix.py b/reproject/healpix/tests/test_healpix.py
@@ -138,3 +138,45 @@ def test_reproject_invalid_order():
             os.path.join(DATA, "bayestar.fits.gz"), reference_header, order="bicubic"
         )
     assert exc.value.args[0] == "Only nearest-neighbor and bilinear interpolation are supported"
+
+
+def test_reproject_to_healpix_input_types(valid_celestial_input_data):
+    array_ref, wcs_in_ref, input_value, kwargs_in = valid_celestial_input_data
+
+    # Compute reference
+
+    healpix_data_ref, footprint_ref = reproject_to_healpix((array_ref, wcs_in_ref), "C", nside=64)
+
+    # Compute test
+
+    healpix_data_test, footprint_test = reproject_to_healpix(
+        input_value, "C", nside=64, **kwargs_in
+    )
+
+    # Make sure there are some valid values
+
+    assert np.sum(~np.isnan(healpix_data_ref)) == 3
+
+    np.testing.assert_allclose(healpix_data_ref, healpix_data_test)
+    np.testing.assert_allclose(footprint_ref, footprint_test)
+
+
+def test_reproject_from_healpix_output_types(valid_celestial_output_projections):
+    wcs_out_ref, shape_ref, output_value, kwargs_out = valid_celestial_output_projections
+
+    array_input = np.random.random(12 * 64**2)
+
+    # Compute reference
+
+    output_ref, footprint_ref = reproject_from_healpix(
+        (array_input, "C"), wcs_out_ref, nested=True, shape_out=shape_ref
+    )
+
+    # Compute test
+
+    output_test, footprint_test = reproject_from_healpix(
+        (array_input, "C"), output_value, nested=True, **kwargs_out
+    )
+
+    np.testing.assert_allclose(output_ref, output_test)
+    np.testing.assert_allclose(footprint_ref, footprint_test)