FA-78902 / Image orientation metadata / Member archive

Region mapping treats an unknown tag as upright · case 02

Corrupt orientation values silently produce boxes as though the image were unrotated.

Member previewVariant 2 · 3 implementations · 8 checks per implementation

Case contract

Map a half-open face/crop region [x, y, width, height] given in stored pixel space of an image of size [w, h] into displayed space for orientation tag 1..8. The region is first clipped to the stored image; an empty clipped region returns None, and an unknown tag returns None. Mirroring a half-open interval [a, b) over extent e gives [e-b, e-a); tags 5..8 exchange axes after the flips.

Why this case matters

Camera, phone and scanner images carry an orientation hint separately from the stored pixels; galleries, thumbnailers, editors and upload pipelines must interpret it consistently or photos appear sideways, mirrored or doubly rotated.

One recorded failure

Sample boundary fixture

This sample comes from the broken implementation of a controlled reproducer.

Boundary fixture	Actual	Expected	Outcome
regression: unknown tag handling 0	`[1, 0, 2, 2]`	`null`	Failed

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