Summary

This PR adds a new feature to the google photos rclone backend: automatic mapping of EXIF/IPTC/XMP image metadata to the Google Photos description field on upload.

How It Works

Two new configuration options are introduced:

On each upload, if --gphotos-upload-exif-description is set, rclone reads the source file's metadata and searches the configured tag list in order. The first non-empty value found is sent as the description in the mediaItems:batchCreate API call.

Namespace Prefixes and Custom XMP Parser

To distinguish between tags of the same name across different metadata blocks, fields can be prefixed with their namespace (e.g., EXIF:, IPTC:, XMP-dc:, XMP-photoshop:).

While the github.com/bep/imagemeta library is used to extract raw EXIF, IPTC, and XMP segments, it only parses simple key-value attributes and does not decode nested XML/RDF structures (such as Dublin Core metadata elements). To support these structures (e.g., nested <dc:title> tags generated by Adobe Lightroom Classic), this PR implements a custom XML pull-parser inside extractEXIFDescription.

Values are trimmed.

Tag Priority (default order)

The default field list reflects common conventions across modern and legacy metadata editors:

1. XMP-dc:Description — Modern Dublin Core description (Lightroom / capture software)
2. IPTC:Caption-Abstract — Legacy IPTC caption abstract (journalism standard)
3. EXIF:ImageDescription — Baseline EXIF hardware/camera description
4. XMP-dc:Title — Dublin Core title panel
5. IPTC:ObjectName — Legacy IPTC object name / title
6. XMP-photoshop:Headline — Modern Photoshop headline tag
7. IPTC:Headline — Legacy IPTC headline tag

Configuration Example

[myphotos]
type = google photos
upload_exif_description = true
exif_description_fields = XMP-dc:Description,IPTC:Caption-Abstract,EXIF:ImageDescription

Or on the command line:

rclone copy ~/Photos/ gphotos:album/MyAlbum \
  --gphotos-upload-exif-description \
  --gphotos-exif-description-fields "XMP-dc:Description,IPTC:Caption-Abstract,EXIF:ImageDescription"

Manual Test Results

Prerequisites

# Build rclone
go build .

# Create test photo with EXIF description
mkdir test_photos_exif
curl -L -o test_photos_exif/image.jpg https://picsum.photos/400/300
exiftool -ImageDescription="Scenic Sunset Over Mountains" test_photos_exif/image.jpg

Step 1: Upload and Verify Description Mapping

./rclone copy test_photos_exif/image.jpg gphotos:album/rclone_Metadata_Test/ \
  --gphotos-upload-exif-description -vv

Expected: file is uploaded successfully. Verify in the Google Photos web UI (https://photos.google.com):

1. Open the rclone_Metadata_Test album and click image.jpg.
2. Select the ⓘ (Info) icon.
3. Confirm the description field shows "Scenic Sunset Over Mountains" ✓

Step 2: Hasher Integration — Detecting Metadata-Only Changes

Using the hasher backend overlay, the local BoltDB cache tracks MD5 checksums. Because changing EXIF metadata modifies the file's binary content, hasher correctly detects the change and triggers a re-upload.

# Configure hasher overlay (if not already done)
rclone config create gphotos_cache hasher remote=gphotos: hashes=md5 max_age=24h

# Initial upload — hash computed in-flight and cached
./rclone copy test_photos_exif/image.jpg gphotos_cache:album/rclone_Metadata_Test/ \
  --gphotos-upload-exif-description --gphotos-batch-mode=sync \
  --ignore-size --ignore-checksum -vv
# → 2026/.../INFO : image.jpg: Copied (new)

# Second run — hash found in cache, skipped
./rclone copy test_photos_exif/image.jpg gphotos_cache:album/rclone_Metadata_Test/ \
  --gphotos-upload-exif-description --gphotos-batch-mode=sync \
  --ignore-size --ignore-checksum -vv
# → There was nothing to transfer

# Modify EXIF description locally
exiftool -ImageDescription="Spectacular Mountain Range" test_photos_exif/image.jpg

# Third run — MD5 changed, triggers re-upload with new description
./rclone copy test_photos_exif/image.jpg gphotos_cache:album/rclone_Metadata_Test/ \
  --gphotos-upload-exif-description --gphotos-batch-mode=sync \
  --ignore-size --ignore-checksum -vv
# → 2026/.../INFO : image.jpg: Copied (replaced existing)

Verify in the Google Photos web UI that the description for image.jpg in rclone_Metadata_Test now shows "Spectacular Mountain Range" ✓

Automated Tests

Self-contained unit tests are added to verify the metadata extraction:

• TestEXIFDescriptionMapping: Mocks the batch upload flow using an in-memory TIFF file with an EXIF ImageDescription tag.
• TestExtractEXIFDescriptionXMP: Mocks the Dublin Core nested XMP tag parsing flow using an in-memory TIFF with a synthesized XMP block.

$ go test -v ./backend/googlephotos/...
=== RUN   TestEXIFDescriptionMapping
--- PASS: TestEXIFDescriptionMapping (0.00s)
=== RUN   TestExtractEXIFDescriptionXMP
--- PASS: TestExtractEXIFDescriptionXMP (0.00s)
...all other existing tests PASS...
ok  	github.com/rclone/rclone/backend/googlephotos	1.339s

Notes

• No EXIF extraction happens when --gphotos-upload-exif-description is not set (zero performance impact by default).
• If no matching tag is found, the description is left empty (no error).
• The tag list is user-configurable to accommodate different metadata workflows (Lightroom, Darktable, camera-native EXIF, etc.).

Dependencies (gh-stack)

This PR is independent and has no dependencies.

Was the change discussed in an issue or in the forum before?

As far as I know, this was not discussed previously. This is a new feature to map EXIF/IPTC/XMP description metadata to Google Photos descriptions on upload.

Checklist

• I have read the contribution guidelines.
• I have added tests for all changes in this PR if appropriate.
• I have added documentation for the changes if appropriate.
• All commit messages are in house style.
• I'm done, this Pull Request is ready for review :-)