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fix: Image.metadata() missing camera-specific Exif sub-IFD tags #91

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Merged
petercorke merged 1 commit into from
Aug 16, 2026
Merged

fix: Image.metadata() missing camera-specific Exif sub-IFD tags #91

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8 changes: 8 additions & 0 deletions src/machinevisiontoolbox/ImageIO.py
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Original file line number Diff line number Diff line change
Expand Up @@ -267,6 +267,14 @@ def metadata(self, key: str | None = None) -> Any:
# map tag number to tag name
exif[TAGS[tag]] = value

# Camera-specific tags (FocalLength, ExposureTime, FNumber,
# ISOSpeedRatings, LensModel, ...) live in a separate "Exif" sub-IFD
# that Image.getexif() does not flatten into the top-level dict --
# 0x8769 is the fixed EXIF-spec tag id for the pointer to it.
for tag, value in meta.get_ifd(0x8769).items():
if tag in TAGS:
exif[TAGS[tag]] = value

if key is None:
return exif
else:
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21 changes: 15 additions & 6 deletions tests/test_image_io.py
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Expand Up @@ -190,14 +190,23 @@ def test_disp(self):
# im.disp(block=False)
pass

# new test
def test_metadata(self):
"""Test reading image metadata"""
# TODO: Test with image file that has metadata
# im = Image.Read('test_image.jpg')
# metadata = im.metadata()
# self.assertIsNotNone(metadata)
pass
im = Image.Read("walls-l.png")
metadata = im.metadata()
self.assertIsNotNone(metadata)

# top-level IFD0 tags
self.assertEqual(metadata["Make"], "Apple")
self.assertEqual(metadata["Model"], "iPhone 5s")
self.assertEqual(im.metadata("Make"), "Apple")

# camera-specific tags live in a separate "Exif" sub-IFD that
# Image.getexif() doesn't flatten into the top-level dict --
# regression test for that sub-IFD merge
self.assertIn("FocalLength", metadata)
self.assertAlmostEqual(im.metadata("FocalLength"), 4.15)
self.assertAlmostEqual(metadata["FNumber"], 2.2)

# new test
def test_showpixels(self):
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