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FA-79231 / Image orientation metadata / Open access

Print size uses round-half-even · case 01

Exact half tenths such as 2.5 are rounded down on some sizes and up on others.

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

ROOT CAUSE

round() on a Fraction rounds ties to even instead of half up.

VERIFIED REPAIR

Add one half and floor.

Unsuccessful approach: Flooring truncates every fractional tenth.

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.

1 / The failure

Exit 1
"""Failure Map reference implementation. Python standard library only."""
import json
import math
from fractions import Fraction
N = 1
observations = []
def solve(d):
    w, h = d['w'], d['h']
    tag = d.get('tag', 1)
    unit = d.get('unit', 2)
    per = {2: Fraction(254, 10), 3: Fraction(10)}.get(unit)
    if per is None:
        return None
    xn, xd = d['xres']
    yn, yd = d.get('yres', d['xres'])
    if xn <= 0 or xd <= 0 or yn <= 0 or yd <= 0:
        return None
    xr = Fraction(xn, xd)
    yr = Fraction(yn, yd)
    if tag in (5, 6, 7, 8):
        w, h, xr, yr = h, w, yr, xr
    def tenths(px, r):
        return round(px * per * 10 / r)
    return [tenths(w, xr), tenths(h, yr)]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[[{'w': 3158, 'h': 1553, 'tag': 6, 'unit': 3, 'xres': [1000, 3], 'yres': [40, 1]}, [3883, 947]], [{'w': 2042, 'h': 678, 'unit': 3, 'xres': [150, 2]}, [2723, 904]], [{'w': 3779, 'h': 386, 'tag': 2, 'unit': 3, 'xres': [200, 3], 'yres': [600, 1]}, [5669, 64]], [{'w': 2250, 'h': 3721, 'tag': 6, 'xres': [300, 1]}, [3150, 1905]], [{'w': 2577, 'h': 2775, 'tag': 6, 'xres': [0, 1]}, None], [{'w': 3942, 'h': 988, 'tag': 8, 'unit': 3, 'xres': [72, 1]}, [1372, 5475]], [{'w': 2676, 'h': 1814, 'tag': 6, 'unit': 3, 'xres': [300, 1], 'yres': [600, 1]}, [302, 892]], [{'w': 3064, 'h': 189, 'tag': 2, 'unit': 3, 'xres': [7200, 100]}, [4256, 263]]], [[{'w': 2030, 'h': 636, 'tag': 6, 'unit': 2, 'xres': [40, 1], 'yres': [96, 1]}, [1683, 12891]], [{'w': 3266, 'h': 1419, 'tag': 5, 'unit': 3, 'xres': [300, 1], 'yres': [1000, 3]}, [426, 1089]], [{'w': 450, 'h': 3183, 'tag': 8, 'unit': 3, 'xres': [200, 3]}, [4775, 675]], [{'w': 1360, 'h': 1067, 'tag': 7, 'xres': [300, 1]}, [903, 1151]], [{'w': 553, 'h': 1044, 'tag': 8, 'unit': 2, 'xres': [200, 3], 'yres': [-300, 1]}, None], [{'w': 2636, 'h': 3063, 'unit': 3, 'xres': [200, 3], 'yres': [300, 1]}, [3954, 1021]], [{'w': 3188, 'h': 3159, 'tag': 1, 'unit': 2, 'xres': [1000, 3]}, [2429, 2407]], [{'w': 3609, 'h': 3681, 'tag': 8, 'unit': 3, 'xres': [300, 1], 'yres': [40, 1]}, [9203, 1203]]], [[{'w': 3617, 'h': 3685, 'tag': 1, 'unit': 3, 'xres': [40, 1]}, [9043, 9213]], [{'w': 3823, 'h': 2286, 'tag': 8, 'unit': 3, 'xres': [150, 2], 'yres': [1000, 3]}, [686, 5097]], [{'w': 2508, 'h': 632, 'tag': 2, 'unit': 3, 'xres': [96, 1]}, [2613, 658]], [{'w': 724, 'h': 1179, 'unit': 2, 'xres': [40, 1], 'yres': [-300, 1]}, None], [{'w': 2151, 'h': 2111, 'tag': 5, 'unit': 2, 'xres': [7200, 100]}, [7447, 7588]], [{'w': 3633, 'h': 2881, 'xres': [-72, 1]}, None], [{'w': 1570, 'h': 1390, 'tag': 8, 'unit': 1, 'xres': [40, 1], 'yres': [72, 1]}, None], [{'w': 746, 'h': 1989, 'tag': 3, 'unit': 3, 'xres': [7200, 100], 'yres': [40, 1]}, [1036, 4973]]], [[{'w': 2404, 'h': 1499, 'tag': 8, 'unit': 3, 'xres': [200, 3]}, [2249, 3606]], [{'w': 47, 'h': 947, 'tag': 8, 'unit': 2, 'xres': [7200, 100]}, [3341, 166]], [{'w': 3, 'h': 5, 'unit': 3, 'xres': [40, 1], 'yres': [40, 1]}, [8, 13]], [{'w': 2120, 'h': 3278, 'tag': 5, 'xres': [1000, 3], 'yres': [40, 1]}, [20815, 1615]], [{'w': 1, 'h': 3356, 'tag': 7, 'xres': [-72, 1], 'yres': [96, 1]}, None], [{'w': 776, 'h': 1736, 'tag': 1, 'unit': 3, 'xres': [96, 1]}, [808, 1808]], [{'w': 1975, 'h': 3847, 'tag': 8, 'unit': 2, 'xres': [72, 1], 'yres': [40, 1]}, [24428, 6967]], [{'w': 246, 'h': 1767, 'tag': 1, 'unit': 3, 'xres': [200, 3]}, [369, 2651]]], [[{'w': 3870, 'h': 1382, 'tag': 6, 'unit': 2, 'xres': [40, 1], 'yres': [40, 1]}, [8776, 24575]], [{'w': 3285, 'h': 917, 'tag': 3, 'unit': 3, 'xres': [300, 1], 'yres': [72, 1]}, [1095, 1274]], [{'w': 3, 'h': 5, 'unit': 3, 'xres': [40, 1], 'yres': [40, 1]}, [8, 13]], [{'w': 2499, 'h': 800, 'tag': 6, 'xres': [150, 2]}, [2709, 8463]], [{'w': 2070, 'h': 2469, 'tag': 1, 'unit': 3, 'xres': [0, 1], 'yres': [-300, 1]}, None], [{'w': 901, 'h': 2455, 'tag': 6, 'unit': 3, 'xres': [7200, 100], 'yres': [600, 1]}, [409, 1251]], [{'w': 3766, 'h': 3194, 'tag': 8, 'xres': [150, 2], 'yres': [300, 1]}, [2704, 12754]], [{'w': 2426, 'h': 49, 'tag': 6, 'unit': 3, 'xres': [300, 1], 'yres': [40, 1]}, [123, 809]]]]
labels = ["regression: final rounding mode", "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: final rounding mode 0[3882, 947][3883, 947]Failed
repair trap 1[2723, 904][2723, 904]Passed
combined fault 2[5668, 64][5669, 64]Failed
control 3[3150, 1905][3150, 1905]Passed
control 4NoneNonePassed
boundary 5[1372, 5475][1372, 5475]Passed
boundary 6[302, 892][302, 892]Passed
control 7[4256, 262][4256, 263]Failed

SHA-256 / 9737b7d6d02aa2fabcea59f93984004dee8157c32450698022a9790a6255b855

2 / The unsuccessful fix

Exit 1
"""Failure Map reference implementation. Python standard library only."""
import json
import math
from fractions import Fraction
N = 1
observations = []
def solve(d):
    w, h = d['w'], d['h']
    tag = d.get('tag', 1)
    unit = d.get('unit', 2)
    per = {2: Fraction(254, 10), 3: Fraction(10)}.get(unit)
    if per is None:
        return None
    xn, xd = d['xres']
    yn, yd = d.get('yres', d['xres'])
    if xn <= 0 or xd <= 0 or yn <= 0 or yd <= 0:
        return None
    xr = Fraction(xn, xd)
    yr = Fraction(yn, yd)
    if tag in (5, 6, 7, 8):
        w, h, xr, yr = h, w, yr, xr
    def tenths(px, r):
        return math.floor(px * per * 10 / r)
    return [tenths(w, xr), tenths(h, yr)]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[[{'w': 3158, 'h': 1553, 'tag': 6, 'unit': 3, 'xres': [1000, 3], 'yres': [40, 1]}, [3883, 947]], [{'w': 2042, 'h': 678, 'unit': 3, 'xres': [150, 2]}, [2723, 904]], [{'w': 3779, 'h': 386, 'tag': 2, 'unit': 3, 'xres': [200, 3], 'yres': [600, 1]}, [5669, 64]], [{'w': 2250, 'h': 3721, 'tag': 6, 'xres': [300, 1]}, [3150, 1905]], [{'w': 2577, 'h': 2775, 'tag': 6, 'xres': [0, 1]}, None], [{'w': 3942, 'h': 988, 'tag': 8, 'unit': 3, 'xres': [72, 1]}, [1372, 5475]], [{'w': 2676, 'h': 1814, 'tag': 6, 'unit': 3, 'xres': [300, 1], 'yres': [600, 1]}, [302, 892]], [{'w': 3064, 'h': 189, 'tag': 2, 'unit': 3, 'xres': [7200, 100]}, [4256, 263]]], [[{'w': 2030, 'h': 636, 'tag': 6, 'unit': 2, 'xres': [40, 1], 'yres': [96, 1]}, [1683, 12891]], [{'w': 3266, 'h': 1419, 'tag': 5, 'unit': 3, 'xres': [300, 1], 'yres': [1000, 3]}, [426, 1089]], [{'w': 450, 'h': 3183, 'tag': 8, 'unit': 3, 'xres': [200, 3]}, [4775, 675]], [{'w': 1360, 'h': 1067, 'tag': 7, 'xres': [300, 1]}, [903, 1151]], [{'w': 553, 'h': 1044, 'tag': 8, 'unit': 2, 'xres': [200, 3], 'yres': [-300, 1]}, None], [{'w': 2636, 'h': 3063, 'unit': 3, 'xres': [200, 3], 'yres': [300, 1]}, [3954, 1021]], [{'w': 3188, 'h': 3159, 'tag': 1, 'unit': 2, 'xres': [1000, 3]}, [2429, 2407]], [{'w': 3609, 'h': 3681, 'tag': 8, 'unit': 3, 'xres': [300, 1], 'yres': [40, 1]}, [9203, 1203]]], [[{'w': 3617, 'h': 3685, 'tag': 1, 'unit': 3, 'xres': [40, 1]}, [9043, 9213]], [{'w': 3823, 'h': 2286, 'tag': 8, 'unit': 3, 'xres': [150, 2], 'yres': [1000, 3]}, [686, 5097]], [{'w': 2508, 'h': 632, 'tag': 2, 'unit': 3, 'xres': [96, 1]}, [2613, 658]], [{'w': 724, 'h': 1179, 'unit': 2, 'xres': [40, 1], 'yres': [-300, 1]}, None], [{'w': 2151, 'h': 2111, 'tag': 5, 'unit': 2, 'xres': [7200, 100]}, [7447, 7588]], [{'w': 3633, 'h': 2881, 'xres': [-72, 1]}, None], [{'w': 1570, 'h': 1390, 'tag': 8, 'unit': 1, 'xres': [40, 1], 'yres': [72, 1]}, None], [{'w': 746, 'h': 1989, 'tag': 3, 'unit': 3, 'xres': [7200, 100], 'yres': [40, 1]}, [1036, 4973]]], [[{'w': 2404, 'h': 1499, 'tag': 8, 'unit': 3, 'xres': [200, 3]}, [2249, 3606]], [{'w': 47, 'h': 947, 'tag': 8, 'unit': 2, 'xres': [7200, 100]}, [3341, 166]], [{'w': 3, 'h': 5, 'unit': 3, 'xres': [40, 1], 'yres': [40, 1]}, [8, 13]], [{'w': 2120, 'h': 3278, 'tag': 5, 'xres': [1000, 3], 'yres': [40, 1]}, [20815, 1615]], [{'w': 1, 'h': 3356, 'tag': 7, 'xres': [-72, 1], 'yres': [96, 1]}, None], [{'w': 776, 'h': 1736, 'tag': 1, 'unit': 3, 'xres': [96, 1]}, [808, 1808]], [{'w': 1975, 'h': 3847, 'tag': 8, 'unit': 2, 'xres': [72, 1], 'yres': [40, 1]}, [24428, 6967]], [{'w': 246, 'h': 1767, 'tag': 1, 'unit': 3, 'xres': [200, 3]}, [369, 2651]]], [[{'w': 3870, 'h': 1382, 'tag': 6, 'unit': 2, 'xres': [40, 1], 'yres': [40, 1]}, [8776, 24575]], [{'w': 3285, 'h': 917, 'tag': 3, 'unit': 3, 'xres': [300, 1], 'yres': [72, 1]}, [1095, 1274]], [{'w': 3, 'h': 5, 'unit': 3, 'xres': [40, 1], 'yres': [40, 1]}, [8, 13]], [{'w': 2499, 'h': 800, 'tag': 6, 'xres': [150, 2]}, [2709, 8463]], [{'w': 2070, 'h': 2469, 'tag': 1, 'unit': 3, 'xres': [0, 1], 'yres': [-300, 1]}, None], [{'w': 901, 'h': 2455, 'tag': 6, 'unit': 3, 'xres': [7200, 100], 'yres': [600, 1]}, [409, 1251]], [{'w': 3766, 'h': 3194, 'tag': 8, 'xres': [150, 2], 'yres': [300, 1]}, [2704, 12754]], [{'w': 2426, 'h': 49, 'tag': 6, 'unit': 3, 'xres': [300, 1], 'yres': [40, 1]}, [123, 809]]]]
labels = ["regression: final rounding mode", "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: final rounding mode 0[3882, 947][3883, 947]Failed
repair trap 1[2722, 904][2723, 904]Failed
combined fault 2[5668, 64][5669, 64]Failed
control 3[3150, 1905][3150, 1905]Passed
control 4NoneNonePassed
boundary 5[1372, 5475][1372, 5475]Passed
boundary 6[302, 892][302, 892]Passed
control 7[4255, 262][4256, 263]Failed

SHA-256 / fc493f83ab5fc634c98b72d50bb565e21b52b5929ac7f614c1baa1c50193b183

3 / The verified repair

Exit 0
"""Failure Map reference implementation. Python standard library only."""
import json
import math
from fractions import Fraction
N = 1
observations = []
def solve(d):
    w, h = d['w'], d['h']
    tag = d.get('tag', 1)
    unit = d.get('unit', 2)
    per = {2: Fraction(254, 10), 3: Fraction(10)}.get(unit)
    if per is None:
        return None
    xn, xd = d['xres']
    yn, yd = d.get('yres', d['xres'])
    if xn <= 0 or xd <= 0 or yn <= 0 or yd <= 0:
        return None
    xr = Fraction(xn, xd)
    yr = Fraction(yn, yd)
    if tag in (5, 6, 7, 8):
        w, h, xr, yr = h, w, yr, xr
    def tenths(px, r):
        return math.floor(px * per * 10 / r + Fraction(1, 2))
    return [tenths(w, xr), tenths(h, yr)]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[[{'w': 3158, 'h': 1553, 'tag': 6, 'unit': 3, 'xres': [1000, 3], 'yres': [40, 1]}, [3883, 947]], [{'w': 2042, 'h': 678, 'unit': 3, 'xres': [150, 2]}, [2723, 904]], [{'w': 3779, 'h': 386, 'tag': 2, 'unit': 3, 'xres': [200, 3], 'yres': [600, 1]}, [5669, 64]], [{'w': 2250, 'h': 3721, 'tag': 6, 'xres': [300, 1]}, [3150, 1905]], [{'w': 2577, 'h': 2775, 'tag': 6, 'xres': [0, 1]}, None], [{'w': 3942, 'h': 988, 'tag': 8, 'unit': 3, 'xres': [72, 1]}, [1372, 5475]], [{'w': 2676, 'h': 1814, 'tag': 6, 'unit': 3, 'xres': [300, 1], 'yres': [600, 1]}, [302, 892]], [{'w': 3064, 'h': 189, 'tag': 2, 'unit': 3, 'xres': [7200, 100]}, [4256, 263]]], [[{'w': 2030, 'h': 636, 'tag': 6, 'unit': 2, 'xres': [40, 1], 'yres': [96, 1]}, [1683, 12891]], [{'w': 3266, 'h': 1419, 'tag': 5, 'unit': 3, 'xres': [300, 1], 'yres': [1000, 3]}, [426, 1089]], [{'w': 450, 'h': 3183, 'tag': 8, 'unit': 3, 'xres': [200, 3]}, [4775, 675]], [{'w': 1360, 'h': 1067, 'tag': 7, 'xres': [300, 1]}, [903, 1151]], [{'w': 553, 'h': 1044, 'tag': 8, 'unit': 2, 'xres': [200, 3], 'yres': [-300, 1]}, None], [{'w': 2636, 'h': 3063, 'unit': 3, 'xres': [200, 3], 'yres': [300, 1]}, [3954, 1021]], [{'w': 3188, 'h': 3159, 'tag': 1, 'unit': 2, 'xres': [1000, 3]}, [2429, 2407]], [{'w': 3609, 'h': 3681, 'tag': 8, 'unit': 3, 'xres': [300, 1], 'yres': [40, 1]}, [9203, 1203]]], [[{'w': 3617, 'h': 3685, 'tag': 1, 'unit': 3, 'xres': [40, 1]}, [9043, 9213]], [{'w': 3823, 'h': 2286, 'tag': 8, 'unit': 3, 'xres': [150, 2], 'yres': [1000, 3]}, [686, 5097]], [{'w': 2508, 'h': 632, 'tag': 2, 'unit': 3, 'xres': [96, 1]}, [2613, 658]], [{'w': 724, 'h': 1179, 'unit': 2, 'xres': [40, 1], 'yres': [-300, 1]}, None], [{'w': 2151, 'h': 2111, 'tag': 5, 'unit': 2, 'xres': [7200, 100]}, [7447, 7588]], [{'w': 3633, 'h': 2881, 'xres': [-72, 1]}, None], [{'w': 1570, 'h': 1390, 'tag': 8, 'unit': 1, 'xres': [40, 1], 'yres': [72, 1]}, None], [{'w': 746, 'h': 1989, 'tag': 3, 'unit': 3, 'xres': [7200, 100], 'yres': [40, 1]}, [1036, 4973]]], [[{'w': 2404, 'h': 1499, 'tag': 8, 'unit': 3, 'xres': [200, 3]}, [2249, 3606]], [{'w': 47, 'h': 947, 'tag': 8, 'unit': 2, 'xres': [7200, 100]}, [3341, 166]], [{'w': 3, 'h': 5, 'unit': 3, 'xres': [40, 1], 'yres': [40, 1]}, [8, 13]], [{'w': 2120, 'h': 3278, 'tag': 5, 'xres': [1000, 3], 'yres': [40, 1]}, [20815, 1615]], [{'w': 1, 'h': 3356, 'tag': 7, 'xres': [-72, 1], 'yres': [96, 1]}, None], [{'w': 776, 'h': 1736, 'tag': 1, 'unit': 3, 'xres': [96, 1]}, [808, 1808]], [{'w': 1975, 'h': 3847, 'tag': 8, 'unit': 2, 'xres': [72, 1], 'yres': [40, 1]}, [24428, 6967]], [{'w': 246, 'h': 1767, 'tag': 1, 'unit': 3, 'xres': [200, 3]}, [369, 2651]]], [[{'w': 3870, 'h': 1382, 'tag': 6, 'unit': 2, 'xres': [40, 1], 'yres': [40, 1]}, [8776, 24575]], [{'w': 3285, 'h': 917, 'tag': 3, 'unit': 3, 'xres': [300, 1], 'yres': [72, 1]}, [1095, 1274]], [{'w': 3, 'h': 5, 'unit': 3, 'xres': [40, 1], 'yres': [40, 1]}, [8, 13]], [{'w': 2499, 'h': 800, 'tag': 6, 'xres': [150, 2]}, [2709, 8463]], [{'w': 2070, 'h': 2469, 'tag': 1, 'unit': 3, 'xres': [0, 1], 'yres': [-300, 1]}, None], [{'w': 901, 'h': 2455, 'tag': 6, 'unit': 3, 'xres': [7200, 100], 'yres': [600, 1]}, [409, 1251]], [{'w': 3766, 'h': 3194, 'tag': 8, 'xres': [150, 2], 'yres': [300, 1]}, [2704, 12754]], [{'w': 2426, 'h': 49, 'tag': 6, 'unit': 3, 'xres': [300, 1], 'yres': [40, 1]}, [123, 809]]]]
labels = ["regression: final rounding mode", "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: final rounding mode 0[3883, 947][3883, 947]Passed
repair trap 1[2723, 904][2723, 904]Passed
combined fault 2[5669, 64][5669, 64]Passed
control 3[3150, 1905][3150, 1905]Passed
control 4NoneNonePassed
boundary 5[1372, 5475][1372, 5475]Passed
boundary 6[302, 892][302, 892]Passed
control 7[4256, 263][4256, 263]Passed

SHA-256 / 615763287fd87f0b4af3c2b6d73b1f202c3eb93f67879564e9327182a5374f58

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 2026-09-29T14:49:42.527552+00:00.

Case digest / 75970e20f7c45d1d843421e83e76c1181a1f208443229f98f70282b27c649428