FA-79218 / Image orientation metadata / Member archive

Missing YResolution falls back to 72 dpi · case 03

A 300 dpi scan without a YResolution prints with a stretched height.

Member previewVariant 3 · 3 implementations · 8 checks per implementation

Case contract

Input {w, h, tag?, unit?, xres: [num, den], yres?: [num, den]}. ResolutionUnit 2 is inches (25.4 mm), 3 is centimetres (10 mm), a missing unit defaults to 2 and any other unit has no physical size (None). A missing yres equals xres; non-positive rational parts give None. For tags 5..8 the displayed width comes from the stored height at YResolution. Return displayed [width, height] in tenths of a millimetre, each rounded half up from the exact value.

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: missing YResolution fallback 0	`[426, 1000]`	`[409, 1000]`	Failed

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