Preserve XMP metadata when resizing images, 16bit and 32bit resize support, multithreaded processing by pierotofy · Pull Request #1830 · OpenDroneMap/WebODM

pierotofy · 2026-01-28T17:27:53Z

pierotofy · 2026-01-28T17:50:41Z

Also adds support for resizing multispectral datasets (16bit, 32bit) as it looks like support for these was recently added in Pillow.

Copilot

Pull request overview

Preserves EXIF/XMP metadata when resizing uploaded images (including higher bit-depth TIFFs) to address “Resize does not preserve XMP metadata” (#1828).

Changes:

Upgrades Pillow and adjusts image resizing logic to preserve XMP/EXIF, using exiftool as a fallback.
Expands which image extensions are considered for resizing.
Adds/extends API task tests to validate EXIF/XMP preservation (including a new multispectral TIFF fixture) and installs exiftool in the Docker image.

Reviewed changes

Copilot reviewed 4 out of 6 changed files in this pull request and generated 17 comments.

Show a summary per file

File	Description
requirements.txt	Updates Pillow version to enable improved metadata/bit-depth support.
package.json	Bumps app version.
app/tests/test_api_task.py	Adds assertions verifying EXIF/XMP preservation after resize (uses `exiftool`).
app/models/task.py	Reworks `resize_image` to preserve XMP/EXIF and adds `exiftool` fallback; expands resize file matching to include PNG.
app/fixtures/tiny_drone_image_multispec.tif	Adds a TIFF fixture containing metadata for regression coverage.
Dockerfile	Installs `exiftool` to support metadata-copy fallback and tests.

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Copilot · 2026-01-29T01:39:14Z

app/tests/test_api_task.py

+
+                # Exiftool agrees
+                resized_exif_dump = extract_exif(resized_task.task_path("tiny_drone_image.jpg"))
+                self.assertTrue('''GPS Latitude                    : 41 deg 13' 34.93" N''' in img1_exif_dump)


The EXIF assertion is checking img1_exif_dump instead of the resized image’s dump (resized_exif_dump), so this test can pass even if metadata isn’t preserved on the resized file. Assert against resized_exif_dump here.

Suggested change

self.assertTrue('''GPS Latitude : 41 deg 13' 34.93" N''' in img1_exif_dump)

self.assertTrue('''GPS Latitude : 41 deg 13' 34.93" N''' in resized_exif_dump)

Copilot · 2026-01-29T01:39:14Z

app/models/task.py

+            if xmp is not None and exif is not None:
+                params['xmp'] = xmp
+                params['exif'] = exif
+            else:
+                # This is either a TIFF or an image for which
+                # PIL's simple EXIF/XMP handling code is insufficient
+                exiftool = shutil.which('exiftool')
+                if not exiftool:
+                    raise Exception("Exiftool missing, but needed")


resize_image only uses Pillow to write metadata when BOTH XMP and EXIF are present; if either is missing (common for many JPEGs), the code requires exiftool and will fail resizing when it’s not installed. Consider preserving whichever metadata is available via Pillow (set params['exif'] and/or params['xmp'] independently) and only falling back to exiftool for formats/metadata cases Pillow can’t handle.

Copilot · 2026-01-29T01:39:15Z

app/models/task.py

+            max_side = max(width, height)
+            if max_side < resize_to:
+                logger.warning('You asked to make {} bigger ({} --> {}), but we are not going to do that.'.format(image_path, max_side, resize_to))
+                return {'path': image_path, 'resize_ratio': 1}


The early return when max_side < resize_to bypasses the done callback, which is used by Task.resize_images() to advance progress and cancellation checks. Call the callback before returning (with a 1.0 ratio result) to keep progress/cancel behavior consistent.

Suggested change

return {'path': image_path, 'resize_ratio': 1}

retval = {'path': image_path, 'resize_ratio': 1}

if done is not None:

done(retval)

return retval

Copilot · 2026-01-29T01:39:15Z

app/models/task.py

+    except Exception as e:
        logger.warning("Cannot resize {}: {}.".format(image_path, str(e)))


Catching a blanket Exception here will also swallow programming errors (e.g. NameError/TypeError) and make failures harder to diagnose. Prefer catching the specific Pillow/IO/subprocess exceptions you expect (and let unexpected exceptions surface) while still performing the same cleanup.

Copilot · 2026-01-29T01:39:15Z

app/models/task.py

        plugin_signals.task_resizing_images.send_robust(sender=self.__class__, task_id=self.id)

-        images_path = self.find_all_files_matching(r'.*\.(jpe?g|tiff?)$')
+        images_path = self.find_all_files_matching(r'.*\.(jpe?g|tiff?|png)$')


resize_images() now includes PNGs in the resize set, but the method docstring/comment above still describes resizing JPGs and mentions lack of TIFF support. Update the docstring to match the actual supported extensions/behavior (and confirm PNG is intended).

Copilot · 2026-01-29T01:39:17Z

app/tests/test_api_task.py

+                # Xmp and exif are preserved
+                self.assertTrue(im.info.get('xmp') is not None)
+                self.assertEqual(im.info.get('xmp'), img1_xmp)
+                self.assertTrue(im.info.get('exif') is not None)


assertTrue(a is not b) cannot provide an informative message. Using assertIsNot(a, b) instead will give more informative messages.

Suggested change

self.assertTrue(im.info.get('exif') is not None)

self.assertIsNotNone(im.info.get('exif'))

Copilot · 2026-01-29T01:39:17Z

app/tests/test_api_task.py

+
+                # Exiftool agrees
+                resized_exif_dump = extract_exif(resized_task.task_path("tiny_drone_image.jpg"))
+                self.assertTrue('''GPS Latitude                    : 41 deg 13' 34.93" N''' in img1_exif_dump)


assertTrue(a in b) cannot provide an informative message. Using assertIn(a, b) instead will give more informative messages.

Copilot · 2026-01-29T01:39:17Z

app/tests/test_api_task.py

+                self.assertTrue('''GPS Latitude                    : 41 deg 13' 34.93" N''' in img1_exif_dump)
+
+                resized_xmp_dump = extract_xmp(resized_task.task_path("tiny_drone_image.jpg"))
+                self.assertTrue('<sensefly:CamID>11</sensefly:CamID>' in resized_xmp_dump)


assertTrue(a in b) cannot provide an informative message. Using assertIn(a, b) instead will give more informative messages.

Copilot · 2026-01-29T01:39:18Z

app/tests/test_api_task.py

+            # EXIF/XMP bytes are preserved
+            ms_resized_exif = subprocess.run(['exiftool', resized_task.task_path("tiny_drone_image_multispec.tif")], 
+                        capture_output=True, text=True, check=True).stdout.strip()
+            self.assertTrue('''GPS Latitude                    : 50 deg 58' 53.02" N''' in ms_resized_exif)


assertTrue(a in b) cannot provide an informative message. Using assertIn(a, b) instead will give more informative messages.

Copilot · 2026-01-29T01:39:18Z

app/tests/test_api_task.py

+
+            ms_resized_xmp = subprocess.run(['exiftool', '-xmp', '-b', resized_task.task_path("tiny_drone_image_multispec.tif")], 
+                        capture_output=True, text=True, check=True).stdout.strip()
+            self.assertTrue('MicaSense:CaptureId="CqaClXcmhKgplT0yPCLE"' in ms_resized_xmp)


assertTrue(a in b) cannot provide an informative message. Using assertIn(a, b) instead will give more informative messages.

pierotofy added 3 commits January 28, 2026 12:10

Keep XMP data when resizing images

4ce4d7e

Bump version

b2ff5dd

Support for resizing 16bit, 32bit TIFFs, remove piexif dependency

a40f807

pierotofy changed the title ~~Preserve XMP metadata when resizing images~~ Preserve XMP metadata when resizing images, 16bit and 32bit resize support Jan 28, 2026

pierotofy added 7 commits January 28, 2026 12:54

Revert piexif removal

85c6899

Revert test logic

a846068

Read TIFF exif properly

2d6afcb

Remove redundant close call

7d2c86b

Use exiftool to copy EXIF/XMP meta for TIFFs

cb9f0bb

More EXIF/XMP tests

f2308b9

Remove print

6ae3064

pierotofy requested a review from Copilot January 29, 2026 01:32

Copilot started reviewing on behalf of pierotofy January 29, 2026 01:33 View session

Copilot AI reviewed Jan 29, 2026

View reviewed changes

pierotofy added 2 commits January 29, 2026 11:00

Misc fixes to EXIF/XMP logic

3902e1f

Add multi-threaded image resize

d1f566b

pierotofy changed the title ~~Preserve XMP metadata when resizing images, 16bit and 32bit resize support~~ Preserve XMP metadata when resizing images, 16bit and 32bit resize support, multithreaded processing Jan 29, 2026

Refactor, skip progress test

1104708

pierotofy merged commit 89d9aeb into OpenDroneMap:master Jan 29, 2026
3 checks passed

	self.assertTrue('''GPS Latitude : 41 deg 13' 34.93" N''' in img1_exif_dump)
	self.assertTrue('''GPS Latitude : 41 deg 13' 34.93" N''' in resized_exif_dump)

-                return {'path': image_path, 'resize_ratio': 1}
+                retval = {'path': image_path, 'resize_ratio': 1}
+                if done is not None:
+                    done(retval)
+                return retval

		except Exception as e:
		logger.warning("Cannot resize {}: {}.".format(image_path, str(e)))

	self.assertTrue(im.info.get('exif') is not None)
	self.assertIsNotNone(im.info.get('exif'))

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pierotofy commented Jan 28, 2026

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