Orientation tag (274) is silently ignored on read

[brendancol]

Problem

TIFF tag 274 (Orientation) values 1-8 specify how rows and columns map to display orientation. The default is 1 (top-left). The reader never reads this tag, so files with non-default orientation decode to silently flipped or rotated arrays — pixel values are correct, geometry is wrong.

Where

xrspatial/geotiff/_header.py and xrspatial/geotiff/_geotags.py — Orientation tag is not in the parse list, and no read path applies an orientation transform.

Repro

import tifffile, numpy as np
from xrspatial.geotiff import open_geotiff

arr = np.arange(64, dtype='uint16').reshape(8, 8)
tifffile.imwrite('/tmp/oriented.tif', arr, extratags=[(274, 'H', 1, 4, True)])  # 4 = bottom-left

# Reference using a known-correct decoder
print(tifffile.imread('/tmp/oriented.tif'))  # flipped vertically per orientation=4

# xrspatial returns the raw row order, ignoring orientation
print(open_geotiff('/tmp/oriented.tif').values[0])

Fix sketch

After decode, apply the orientation transform per the TIFF 6.0 spec table:

Value	Transform
1	identity
2	flip horizontally
3	rotate 180
4	flip vertically
5	transpose
6	rotate 90 CW
7	transverse
8	rotate 90 CCW

Coordinate axes need to swap for transposed orientations (5-8). Most camera-produced TIFFs use 1-4; values 5-8 are rare.

Severity

Silent geometric error, not numerical drift. Pixel values are correct but in the wrong positions.