Why a Photo's Face Boxes Move After Cropping or Resizing
By ImgHeal · Updated
A person box can point at the wrong face after a photograph is cropped, mirrored, or resized. The names may still be correct while the coordinates no longer describe the file now being displayed.
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Identify the image that defined the coordinates
Record the exact source version, its pixel width and height, orientation, and the tool or record that stores the annotations. Determine whether positions are expressed as pixels, percentages, or another coordinate system. Do not assume two files with the same visible scene share a coordinate space. A crop can remove the original origin, while an orientation change can swap or reverse axes. Preserve an unannotated source and the original region data before attempting any transfer.
Account for each geometric change in order
For a simple pixel-coordinate example, removing 200 pixels from the left and 100 from the top changes a point at 350,250 to 150,150 in the cropped image. Resizing that crop to half its dimensions changes the point again to 75,75. Boxes and polygons need all their relevant boundaries transformed, not just one label. This simple translation-and-scale example does not cover rotation, mirroring, perspective correction, or a provider's different conventions; use the tool's supported transformation workflow where possible.
Check every transferred region on the delivered file
Overlay or inspect the transformed annotations against the exact final copy. Check edge people, partly cropped regions, and labels near an image boundary. Retain stable person identifiers even when a displayed region needs revision, and note which source version supplied the evidence. W3C's annotation model ties a region target to a resource; a coordinate list without that resource context is incomplete. If an ImgHeal output changes geometry or recognizable features, recheck the regions manually instead of treating successful file transfer as proof that every name still points to the intended person.
Check before sharing this record
- Record the target image version and dimensions.
- Respect crop, scale, orientation, and coordinate units.
- Inspect every region on the final shared copy.
Sources and further reading
- W3C: Web Annotation Data ModelAnnotations identify a target resource or region; coordinates only make sense with the correct image and version.
Questions about this restoration task
Can I copy pixel boxes unchanged to a half-size export?
Not reliably. Pixel coordinates refer to a particular coordinate space. Apply the appropriate supported transform and verify the result on the actual exported file.
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