Victor Kuznetsov 646f72534b Carry the ICC profile and EXIF orientation across re-encodes ...

Issue #98. cv2's encoders write no container metadata, so every pixel-path
output (all, visible, invisible, erase) came back without its colour profile
and orientation tag, even with --keep-metadata.

imwrite now takes display_tags_from, the file whose decode produced the
pixels, and restores the two display tags into the re-encoded output: PNG and
JPEG by splicing iCCP/eXIf chunks and APP1/APP2 segments into the encoded
bytes, WebP by a lossless Pillow re-save (libwebp hides hand-spliced chunks
from readers without a VP8X header), HEIF through the save call itself.
Orientation is re-tagged only when the raster still has the source's stored
dimensions: cv2 rotates JPEG and (build-dependent) PNG decodes under
IMREAD_COLOR but never IMREAD_UNCHANGED, which is what the pixel paths read
with, so the decision is made against the raster's own shape and cannot
double-rotate.

The default metadata strip now preserves what the restore put back: the PIL
path forwards the profile and a scrubbed EXIF (orientation included) for PNG
and WebP outputs, the 16-bit chunk walker re-emits eXIf scrubbed instead of
dropping it wholesale, and --remove-all actually drops the ICC profile on
every format (Pillow's saver fallback kept it alive, contradicting the
documented "removed by --remove-all").

Mirror and 180-degree orientations (2, 3, 4) stay untagged: no cheap signal
distinguishes a rotated decode from a stored one for them.

2026-09-06 14:41:19 -07:00

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piexif

Carry the ICC profile and EXIF orientation across re-encodes

2026-09-06 14:41:19 -07:00