geotiff: forward photometric through VRT writer (#1861)

xrspatial/geotiff/__init__.py

@@ -1389,7 +1389,8 @@ def to_geotiff(data: xr.DataArray | np.ndarray,
                          tile_size=tile_size,
                          predictor=predictor,
                          bigtiff=bigtiff,
-                         max_z_error=max_z_error)
+                         max_z_error=max_z_error,
+                         photometric=photometric)
         return
 
     # Auto-detect GPU data and dispatch to write_geotiff_gpu. ``gpu is
@@ -1678,7 +1679,8 @@ def _write_single_tile(chunk_data, path, geo_transform, epsg, wkt,
                        y_resolution=None,
                        resolution_unit=None,
                        gdal_metadata_xml=None,
-                       extra_tags=None):
+                       extra_tags=None,
+                       photometric: str | int = 'auto'):
     """Write a single tile GeoTIFF. Used by _write_vrt_tiled.
 
     Forwards the same rich-tag set that ``to_geotiff`` passes through to
@@ -1730,13 +1732,15 @@ def _write_single_tile(chunk_data, path, geo_transform, epsg, wkt,
           gdal_metadata_xml=gdal_metadata_xml,
           extra_tags=extra_tags,
           bigtiff=bigtiff,
-          max_z_error=max_z_error)
+          max_z_error=max_z_error,
+          photometric=photometric)
 
 
 def _write_vrt_tiled(data, vrt_path, *, crs=None, nodata=None,
                      compression='zstd', compression_level=None,
                      tile_size=256, predictor: bool | int = False,
-                     bigtiff=None, max_z_error: float = 0.0):
+                     bigtiff=None, max_z_error: float = 0.0,
+                     photometric: str | int = 'auto'):
     """Write a DataArray as a directory of tiled GeoTIFFs with a VRT index.
 
     This enables streaming dask arrays to disk without materializing the
@@ -1903,7 +1907,8 @@ def _write_vrt_tiled(data, vrt_path, *, crs=None, nodata=None,
                     y_resolution=y_res,
                     resolution_unit=res_unit,
                     gdal_metadata_xml=gdal_meta_xml,
-                    extra_tags=extra_tags_list)
+                    extra_tags=extra_tags_list,
+                    photometric=photometric)
                 delayed_tasks.append(task)
             else:
                 # Numpy: slice and write directly
@@ -1918,7 +1923,8 @@ def _write_vrt_tiled(data, vrt_path, *, crs=None, nodata=None,
                     y_resolution=y_res,
                     resolution_unit=res_unit,
                     gdal_metadata_xml=gdal_meta_xml,
-                    extra_tags=extra_tags_list)
+                    extra_tags=extra_tags_list,
+                    photometric=photometric)
 
             col_offset += chunk_w
         row_offset += chunk_h

xrspatial/geotiff/tests/test_vrt_writer_photometric_1861.py

@@ -0,0 +1,75 @@
+"""Regression test for issue #1861: ``photometric`` dropped by VRT writer.
+
+``to_geotiff(data, '.vrt', photometric=...)`` accepted the kwarg at the
+public boundary but ``_write_vrt_tiled`` did not take ``photometric`` and
+``_write_single_tile`` did not forward it to ``write(...)``. Per-tile
+TIFFs were always tagged with the default Photometric=MinIsBlack (1) no
+matter what the caller requested.
+
+This test pins the fix: the kwarg now threads through to every per-tile
+``write`` call so the on-disk Photometric tag matches the request.
+"""
+from __future__ import annotations
+
+import glob
+import os
+
+import numpy as np
+import xarray as xr
+
+from xrspatial.geotiff import to_geotiff
+from xrspatial.geotiff._header import TAG_PHOTOMETRIC, parse_header, parse_ifd
+
+
+def _read_primary_ifd(path: str):
+    with open(path, 'rb') as f:
+        raw = f.read()
+    hdr = parse_header(raw[:16])
+    return parse_ifd(raw, hdr.first_ifd_offset, hdr)
+
+
+def _tile_paths(vrt_path: str):
+    stem = os.path.splitext(os.path.basename(vrt_path))[0]
+    tiles_dir = os.path.join(
+        os.path.dirname(os.path.abspath(vrt_path)),
+        stem + '_tiles',
+    )
+    return sorted(glob.glob(os.path.join(tiles_dir, 'tile_*.tif')))
+
+
+def test_vrt_writer_forwards_photometric_miniswhite_1861(tmp_path):
+    """photometric='miniswhite' must tag every per-tile TIFF with
+    PhotometricInterpretation = 0 (MinIsWhite)."""
+    arr = np.zeros((48, 48), dtype=np.uint8)
+    da = xr.DataArray(arr, dims=('y', 'x'))
+    vrt_path = str(tmp_path / 'miniswhite_1861.vrt')
+
+    to_geotiff(da, vrt_path, photometric='miniswhite', tile_size=16)
+
+    tiles = _tile_paths(vrt_path)
+    assert tiles, 'expected at least one per-tile TIFF under _tiles/'
+    for tile in tiles:
+        ifd = _read_primary_ifd(tile)
+        assert ifd.get_value(TAG_PHOTOMETRIC) == 0, (
+            f'tile {tile} has Photometric '
+            f'{ifd.get_value(TAG_PHOTOMETRIC)}, expected 0 (MinIsWhite)'
+        )
+
+
+def test_vrt_writer_default_photometric_minisblack_1861(tmp_path):
+    """Control: default photometric='auto' keeps per-tile TIFFs at
+    PhotometricInterpretation = 1 (MinIsBlack)."""
+    arr = np.zeros((48, 48), dtype=np.uint8)
+    da = xr.DataArray(arr, dims=('y', 'x'))
+    vrt_path = str(tmp_path / 'default_auto_1861.vrt')
+
+    to_geotiff(da, vrt_path, tile_size=16)
+
+    tiles = _tile_paths(vrt_path)
+    assert tiles, 'expected at least one per-tile TIFF under _tiles/'
+    for tile in tiles:
+        ifd = _read_primary_ifd(tile)
+        assert ifd.get_value(TAG_PHOTOMETRIC) == 1, (
+            f'tile {tile} has Photometric '
+            f'{ifd.get_value(TAG_PHOTOMETRIC)}, expected 1 (MinIsBlack)'
+        )