FA-79175 / Image orientation metadata / Member archive

Canvas rotation for tag 6 translates by the image width · case 05

Clockwise-rotated photos are drawn partly outside the canvas on non-square images.

Member previewVariant 5 · 3 implementations · 8 checks per implementation

Case contract

Input [w, h, tag]. Produce the canvas size and the 2D affine [a, b, c, d, e, f] (x' = a*x + c*y + e, y' = b*x + d*y + f, continuous coordinates, so mirroring an extent e maps x to e - x) that draws the stored image upright. Tags 5..8 use a [h, w] canvas; invalid tags are treated as 1.

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: tag 6 translation 0	`{"canvas": [2830, 3353], "matrix": [0, 1, -1, 0, 3353, 0]}`	`{"canvas": [2830, 3353], "matrix": [0, 1, -1, 0, 2830, 0]}`	Failed

MEMBER ARCHIVE

The complete case is available to members.

This record includes three runnable implementations, regression fixtures, execution results, and source hashes.

Member access is invitation-based. Sign in with your invited account to inspect the sources.