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FA-79256 / Image orientation metadata / Open access

Upright check compares against an invalid raw tag · case 01

Photos with a corrupt tag of 0 are flagged as mis-rotated even when they display normally.

Verified by executionVariant 1 · 8 checks per implementationDownload source bundle ↓JSON ↗

ROOT CAUSE

The upright check compares with the raw tag instead of the normalised one.

THE FAILURE

The upright check compares with the raw tag instead of the normalised one.

Unsuccessful approach: Comparing the baked pixels ignores what the renderer does afterwards.

Case contract

Predict what a browser shows for a photo that went through an upload pipeline. Input {tag, baked, reset, stripped, css, cross_origin}. Baking applies the tag to the pixels; the remaining tag is 1 if metadata was stripped or if baking also reset the tag, else the original tag. The renderer applies the remaining tag when css is "from-image" or the image is cross-origin (image-orientation: none is ignored cross-origin). Finally the viewer applies its own extra orientation (default 1). Orientations are (k clockwise quarter turns after m mirrors), with applying B after A giving k = k2 + (-k1 if m2 else k1). Invalid tags count as 1. Return [shown_tag, shown == tag].

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.

1 / The failure

Exit 1
"""Failure Map reference implementation. Python standard library only."""
import json

N = 1
observations = []
def solve(p):
    to_km = {1: (0, 0), 2: (0, 1), 3: (2, 0), 4: (2, 1), 5: (3, 1), 6: (1, 0), 7: (1, 1), 8: (3, 0)}
    from_km = {v: t for t, v in to_km.items()}
    def compose(first, second):
        k1, m1 = to_km[first]
        k2, m2 = to_km[second]
        k = (k2 + (-k1 if m2 else k1)) % 4
        return from_km[(k, m1 ^ m2)]
    tag = p['tag'] if p['tag'] in to_km else 1
    pixels = tag if p['baked'] else 1
    if p['stripped']:
        meta = 1
    elif p['baked'] and p['reset']:
        meta = 1
    else:
        meta = tag
    honored = p['css'] == 'from-image' or p['cross_origin']
    shown = compose(compose(pixels, meta if honored else 1), p.get('extra', 1))
    return [shown, shown == p['tag']]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[[{'tag': 0, 'baked': True, 'reset': False, 'stripped': False, 'css': 'from-image', 'cross_origin': False, 'extra': 1}, [1, True]], [{'tag': 7, 'baked': True, 'reset': True, 'stripped': False, 'css': 'none', 'cross_origin': False, 'extra': 3}, [5, False]], [{'tag': 2, 'baked': True, 'reset': True, 'stripped': True, 'css': 'from-image', 'cross_origin': False, 'extra': 1}, [2, True]], [{'tag': 5, 'baked': True, 'reset': True, 'stripped': True, 'css': 'from-image', 'cross_origin': True, 'extra': 1}, [5, True]], [{'tag': 8, 'baked': False, 'reset': True, 'stripped': False, 'css': 'from-image', 'cross_origin': False, 'extra': 2}, [7, False]], [{'tag': 2, 'baked': False, 'reset': False, 'stripped': True, 'css': 'from-image', 'cross_origin': False, 'extra': 1}, [1, False]], [{'tag': 3, 'baked': False, 'reset': False, 'stripped': False, 'css': 'from-image', 'cross_origin': True, 'extra': 2}, [4, False]], [{'tag': 0, 'baked': True, 'reset': True, 'stripped': False, 'css': 'from-image', 'cross_origin': False, 'extra': 1}, [1, True]]], [[{'tag': 0, 'baked': False, 'reset': False, 'stripped': False, 'css': 'from-image', 'cross_origin': True, 'extra': 1}, [1, True]], [{'tag': 8, 'baked': True, 'reset': False, 'stripped': False, 'css': 'none', 'cross_origin': False, 'extra': 7}, [4, False]], [{'tag': 6, 'baked': False, 'reset': True, 'stripped': False, 'css': 'from-image', 'cross_origin': True, 'extra': 8}, [1, False]], [{'tag': 4, 'baked': False, 'reset': True, 'stripped': False, 'css': 'from-image', 'cross_origin': True, 'extra': 2}, [3, False]], [{'tag': 3, 'baked': False, 'reset': False, 'stripped': False, 'css': 'from-image', 'cross_origin': True, 'extra': 7}, [5, False]], [{'tag': 7, 'baked': False, 'reset': False, 'stripped': False, 'css': 'none', 'cross_origin': False, 'extra': 8}, [8, False]], [{'tag': 4, 'baked': False, 'reset': False, 'stripped': False, 'css': 'none', 'cross_origin': False, 'extra': 7}, [7, False]], [{'tag': 0, 'baked': True, 'reset': False, 'stripped': False, 'css': 'from-image', 'cross_origin': False, 'extra': 1}, [1, True]]], [[{'tag': 0, 'baked': False, 'reset': False, 'stripped': False, 'css': 'from-image', 'cross_origin': False, 'extra': 1}, [1, True]], [{'tag': 3, 'baked': True, 'reset': True, 'stripped': True, 'css': 'none', 'cross_origin': False, 'extra': 8}, [6, False]], [{'tag': 6, 'baked': False, 'reset': False, 'stripped': False, 'css': 'none', 'cross_origin': False, 'extra': 3}, [3, False]], [{'tag': 2, 'baked': True, 'reset': False, 'stripped': False, 'css': 'from-image', 'cross_origin': True, 'extra': 2}, [2, True]], [{'tag': 8, 'baked': True, 'reset': True, 'stripped': True, 'css': 'none', 'cross_origin': False, 'extra': 1}, [8, True]], [{'tag': 3, 'baked': False, 'reset': False, 'stripped': False, 'css': 'from-image', 'cross_origin': False, 'extra': 7}, [5, False]], [{'tag': 4, 'baked': False, 'reset': True, 'stripped': False, 'css': 'from-image', 'cross_origin': False, 'extra': 6}, [5, False]], [{'tag': 6, 'baked': True, 'reset': True, 'stripped': False, 'css': 'from-image', 'cross_origin': True, 'extra': 2}, [5, False]]], [[{'tag': 0, 'baked': False, 'reset': False, 'stripped': True, 'css': 'from-image', 'cross_origin': True, 'extra': 1}, [1, True]], [{'tag': 6, 'baked': True, 'reset': False, 'stripped': False, 'css': 'from-image', 'cross_origin': False, 'extra': 5}, [7, False]], [{'tag': 8, 'baked': True, 'reset': False, 'stripped': False, 'css': 'none', 'cross_origin': False, 'extra': 1}, [8, True]], [{'tag': 5, 'baked': False, 'reset': True, 'stripped': False, 'css': 'none', 'cross_origin': False, 'extra': 1}, [1, False]], [{'tag': 7, 'baked': True, 'reset': False, 'stripped': False, 'css': 'from-image', 'cross_origin': False, 'extra': 7}, [7, True]], [{'tag': 8, 'baked': False, 'reset': False, 'stripped': False, 'css': 'none', 'cross_origin': False, 'extra': 1}, [1, False]], [{'tag': 1, 'baked': True, 'reset': True, 'stripped': False, 'css': 'from-image', 'cross_origin': True, 'extra': 1}, [1, True]], [{'tag': 0, 'baked': False, 'reset': True, 'stripped': False, 'css': 'from-image', 'cross_origin': False, 'extra': 1}, [1, True]]], [[{'tag': 0, 'baked': False, 'reset': False, 'stripped': False, 'css': 'none', 'cross_origin': False, 'extra': 1}, [1, True]], [{'tag': 5, 'baked': True, 'reset': False, 'stripped': False, 'css': 'none', 'cross_origin': False, 'extra': 6}, [2, False]], [{'tag': 5, 'baked': False, 'reset': False, 'stripped': True, 'css': 'none', 'cross_origin': False, 'extra': 1}, [1, False]], [{'tag': 8, 'baked': False, 'reset': False, 'stripped': True, 'css': 'from-image', 'cross_origin': True, 'extra': 5}, [5, False]], [{'tag': 6, 'baked': True, 'reset': True, 'stripped': True, 'css': 'none', 'cross_origin': False, 'extra': 1}, [6, True]], [{'tag': 3, 'baked': False, 'reset': False, 'stripped': False, 'css': 'none', 'cross_origin': True, 'extra': 3}, [1, False]], [{'tag': 5, 'baked': False, 'reset': True, 'stripped': True, 'css': 'from-image', 'cross_origin': True, 'extra': 3}, [3, False]], [{'tag': 0, 'baked': True, 'reset': True, 'stripped': True, 'css': 'from-image', 'cross_origin': False, 'extra': 1}, [1, True]]]]
labels = ["regression: upright comparison reference", "repair trap", "combined fault", "control", "control", "boundary", "boundary", "control"]
for i, (args, expected) in enumerate(fixtures[N-1]):
    check("%s %d" % (labels[i % len(labels)], i), solve(args), expected)
print(json.dumps({"observations": observations, "passed": all(x["passed"] for x in observations)}, ensure_ascii=False))
raise SystemExit(0 if all(x["passed"] for x in observations) else 1)
Boundary fixtureActualExpectedOutcome
regression: upright comparison reference 0[1, False][1, True]Failed
repair trap 1[5, False][5, False]Passed
combined fault 2[2, True][2, True]Passed
control 3[5, True][5, True]Passed
control 4[7, False][7, False]Passed
boundary 5[1, False][1, False]Passed
boundary 6[4, False][4, False]Passed
control 7[1, False][1, True]Failed

SHA-256 / 8912e337d99613a540481d11870d1cce72f39da4d04d0a87e7f0894ca69efff5

2 / The unsuccessful fix

Exit 1
"""Failure Map reference implementation. Python standard library only."""
import json

N = 1
observations = []
def solve(p):
    to_km = {1: (0, 0), 2: (0, 1), 3: (2, 0), 4: (2, 1), 5: (3, 1), 6: (1, 0), 7: (1, 1), 8: (3, 0)}
    from_km = {v: t for t, v in to_km.items()}
    def compose(first, second):
        k1, m1 = to_km[first]
        k2, m2 = to_km[second]
        k = (k2 + (-k1 if m2 else k1)) % 4
        return from_km[(k, m1 ^ m2)]
    tag = p['tag'] if p['tag'] in to_km else 1
    pixels = tag if p['baked'] else 1
    if p['stripped']:
        meta = 1
    elif p['baked'] and p['reset']:
        meta = 1
    else:
        meta = tag
    honored = p['css'] == 'from-image' or p['cross_origin']
    shown = compose(compose(pixels, meta if honored else 1), p.get('extra', 1))
    return [shown, pixels == tag]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[[{'tag': 0, 'baked': True, 'reset': False, 'stripped': False, 'css': 'from-image', 'cross_origin': False, 'extra': 1}, [1, True]], [{'tag': 7, 'baked': True, 'reset': True, 'stripped': False, 'css': 'none', 'cross_origin': False, 'extra': 3}, [5, False]], [{'tag': 2, 'baked': True, 'reset': True, 'stripped': True, 'css': 'from-image', 'cross_origin': False, 'extra': 1}, [2, True]], [{'tag': 5, 'baked': True, 'reset': True, 'stripped': True, 'css': 'from-image', 'cross_origin': True, 'extra': 1}, [5, True]], [{'tag': 8, 'baked': False, 'reset': True, 'stripped': False, 'css': 'from-image', 'cross_origin': False, 'extra': 2}, [7, False]], [{'tag': 2, 'baked': False, 'reset': False, 'stripped': True, 'css': 'from-image', 'cross_origin': False, 'extra': 1}, [1, False]], [{'tag': 3, 'baked': False, 'reset': False, 'stripped': False, 'css': 'from-image', 'cross_origin': True, 'extra': 2}, [4, False]], [{'tag': 0, 'baked': True, 'reset': True, 'stripped': False, 'css': 'from-image', 'cross_origin': False, 'extra': 1}, [1, True]]], [[{'tag': 0, 'baked': False, 'reset': False, 'stripped': False, 'css': 'from-image', 'cross_origin': True, 'extra': 1}, [1, True]], [{'tag': 8, 'baked': True, 'reset': False, 'stripped': False, 'css': 'none', 'cross_origin': False, 'extra': 7}, [4, False]], [{'tag': 6, 'baked': False, 'reset': True, 'stripped': False, 'css': 'from-image', 'cross_origin': True, 'extra': 8}, [1, False]], [{'tag': 4, 'baked': False, 'reset': True, 'stripped': False, 'css': 'from-image', 'cross_origin': True, 'extra': 2}, [3, False]], [{'tag': 3, 'baked': False, 'reset': False, 'stripped': False, 'css': 'from-image', 'cross_origin': True, 'extra': 7}, [5, False]], [{'tag': 7, 'baked': False, 'reset': False, 'stripped': False, 'css': 'none', 'cross_origin': False, 'extra': 8}, [8, False]], [{'tag': 4, 'baked': False, 'reset': False, 'stripped': False, 'css': 'none', 'cross_origin': False, 'extra': 7}, [7, False]], [{'tag': 0, 'baked': True, 'reset': False, 'stripped': False, 'css': 'from-image', 'cross_origin': False, 'extra': 1}, [1, True]]], [[{'tag': 0, 'baked': False, 'reset': False, 'stripped': False, 'css': 'from-image', 'cross_origin': False, 'extra': 1}, [1, True]], [{'tag': 3, 'baked': True, 'reset': True, 'stripped': True, 'css': 'none', 'cross_origin': False, 'extra': 8}, [6, False]], [{'tag': 6, 'baked': False, 'reset': False, 'stripped': False, 'css': 'none', 'cross_origin': False, 'extra': 3}, [3, False]], [{'tag': 2, 'baked': True, 'reset': False, 'stripped': False, 'css': 'from-image', 'cross_origin': True, 'extra': 2}, [2, True]], [{'tag': 8, 'baked': True, 'reset': True, 'stripped': True, 'css': 'none', 'cross_origin': False, 'extra': 1}, [8, True]], [{'tag': 3, 'baked': False, 'reset': False, 'stripped': False, 'css': 'from-image', 'cross_origin': False, 'extra': 7}, [5, False]], [{'tag': 4, 'baked': False, 'reset': True, 'stripped': False, 'css': 'from-image', 'cross_origin': False, 'extra': 6}, [5, False]], [{'tag': 6, 'baked': True, 'reset': True, 'stripped': False, 'css': 'from-image', 'cross_origin': True, 'extra': 2}, [5, False]]], [[{'tag': 0, 'baked': False, 'reset': False, 'stripped': True, 'css': 'from-image', 'cross_origin': True, 'extra': 1}, [1, True]], [{'tag': 6, 'baked': True, 'reset': False, 'stripped': False, 'css': 'from-image', 'cross_origin': False, 'extra': 5}, [7, False]], [{'tag': 8, 'baked': True, 'reset': False, 'stripped': False, 'css': 'none', 'cross_origin': False, 'extra': 1}, [8, True]], [{'tag': 5, 'baked': False, 'reset': True, 'stripped': False, 'css': 'none', 'cross_origin': False, 'extra': 1}, [1, False]], [{'tag': 7, 'baked': True, 'reset': False, 'stripped': False, 'css': 'from-image', 'cross_origin': False, 'extra': 7}, [7, True]], [{'tag': 8, 'baked': False, 'reset': False, 'stripped': False, 'css': 'none', 'cross_origin': False, 'extra': 1}, [1, False]], [{'tag': 1, 'baked': True, 'reset': True, 'stripped': False, 'css': 'from-image', 'cross_origin': True, 'extra': 1}, [1, True]], [{'tag': 0, 'baked': False, 'reset': True, 'stripped': False, 'css': 'from-image', 'cross_origin': False, 'extra': 1}, [1, True]]], [[{'tag': 0, 'baked': False, 'reset': False, 'stripped': False, 'css': 'none', 'cross_origin': False, 'extra': 1}, [1, True]], [{'tag': 5, 'baked': True, 'reset': False, 'stripped': False, 'css': 'none', 'cross_origin': False, 'extra': 6}, [2, False]], [{'tag': 5, 'baked': False, 'reset': False, 'stripped': True, 'css': 'none', 'cross_origin': False, 'extra': 1}, [1, False]], [{'tag': 8, 'baked': False, 'reset': False, 'stripped': True, 'css': 'from-image', 'cross_origin': True, 'extra': 5}, [5, False]], [{'tag': 6, 'baked': True, 'reset': True, 'stripped': True, 'css': 'none', 'cross_origin': False, 'extra': 1}, [6, True]], [{'tag': 3, 'baked': False, 'reset': False, 'stripped': False, 'css': 'none', 'cross_origin': True, 'extra': 3}, [1, False]], [{'tag': 5, 'baked': False, 'reset': True, 'stripped': True, 'css': 'from-image', 'cross_origin': True, 'extra': 3}, [3, False]], [{'tag': 0, 'baked': True, 'reset': True, 'stripped': True, 'css': 'from-image', 'cross_origin': False, 'extra': 1}, [1, True]]]]
labels = ["regression: upright comparison reference", "repair trap", "combined fault", "control", "control", "boundary", "boundary", "control"]
for i, (args, expected) in enumerate(fixtures[N-1]):
    check("%s %d" % (labels[i % len(labels)], i), solve(args), expected)
print(json.dumps({"observations": observations, "passed": all(x["passed"] for x in observations)}, ensure_ascii=False))
raise SystemExit(0 if all(x["passed"] for x in observations) else 1)
Boundary fixtureActualExpectedOutcome
regression: upright comparison reference 0[1, True][1, True]Passed
repair trap 1[5, True][5, False]Failed
combined fault 2[2, True][2, True]Passed
control 3[5, True][5, True]Passed
control 4[7, False][7, False]Passed
boundary 5[1, False][1, False]Passed
boundary 6[4, False][4, False]Passed
control 7[1, True][1, True]Passed

SHA-256 / 53cba604ebf86f1222aac1394e3ce83af33c9b33d1b021aacc4a6a4e29f75ac2

HELD IN THE MEMBER ARCHIVE

The verified repair and its recorded checks are member-only.

This mechanism has 8 recorded checks per implementation. The open-access tier publishes the failure and the unsuccessful fix; the repaired source that passes every check, and the observations that prove it, are available to members.

Every case sharing this mechanism uses the same contract and the same repair, so this one record is held back for all of them.

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Verification & scope

A deterministic bounded teaching model with a stipulated contract; it makes no claim of conformance to any published specification. This reproducer isolates one failure mechanism. Results cover the supplied fixtures. Variants within a family share a test contract and should remain grouped when constructing evaluation splits. Related mechanisms with a shared evaluation_group must also remain together; these controlled models are not independent production incidents.

Observations recorded using Python 3.12.14 at 2026-09-29T14:49:43.043684+00:00.

Case digest / f75508950ef37c8b7a8a16aa3dea6db3960cbb4ed8861b6b137308d2d843c724