perceptual op• Data kinds: rgbimage × rgbimage → table
• Call: import fullseye as fs; fs.ledger.fsim_pair(ref, dist, data_range: 'float' = 255.0, downsample: 'bool' = True) -> 'dict' (to call the implementation directly, import iqafsim; iqafsim.fsim_pair(ref, dist, data_range: 'float' = 255.0, downsample: 'bool' = True) -> 'dict'; from the registry, opsimgmetrics.get("fsim_pair"))
> This operator's description has not been translated yet. The original text follows as it is.
FSIM と FSIMc を一度に(位相一致は 1 枚 1 回しか計算しない —— 評価器や PoC はこちらを呼ぶ)。
手順(論文 §III): (1) F = max(1, round(min(H, W)/256)) で F×F 平均 + 間引き(TID2013 の 384×512 は F = 2 → 192×256)、(2) Y の位相一致 PC と
Scharr([3 0 −3; 10 0 −10; 3 0 −3]/16)勾配の大きさ G、(3) S_PC = (2 PC1 PC2 + T1)/(PC1² + PC2² + T1)、S_G = (2 G1 G2 + T2)/(G1² + G2² + T2)、
(4) FSIM = Σ S_G S_PC PC_m / Σ PC_m(PC_m = max(PC1, PC2))、(5) FSIMc は彩度 I / Q の S_I S_Q(T3 = T4 = 200)の λ = 0.03 乗の実部を掛ける。
入力は同じ形の (H, W) か (H, W, 3)(0–255; `data_range` で尺度を宣言)。(H, W) のときは FSIMc = FSIM(彩度の項が無い)。
TID2013 の作者値: FSIM.txt は Y′ limited の灰色画像、FSIMc.txt は色画像(モジュール docstring の表)—— 色画像 1 枚から両方を出すと FSIM の方は
FSIM.txt と合わない(max 0.0318)。返り値 `{"fsim", "fsimc", "f"}`(f = 間引き係数)。恒等で 1。
Raises `ValueError`: 形が違う、2×2 未満、位相一致が全画素 0(平坦画像: FSIM は 0/0 で定義されない)。
• image_difference_metrics family guide
• Sample-data catalog (download URLs / licences) — 2-D uses skimage.data (BSD/public domain) plus synthetic images; 3-D lists download URLs for real data sources (Stanford, PDS, …).
• Operator provenance and references — the sources of the research/methods this op family came from.
• The canonical algorithm (author, year) and its uses are named in the family usage guide above.
• poc_iqa_fsim_gmsd_vif — py -3.11 examples/poc_iqa_fsim_gmsd_vif.py
table as input)luma_limited_u8 · rank_data · tid2013_index · tid2013_by_distortion
perceptual)fsim · fsimc · gmsd · gmsd_map · vifp · phase_congruency_pc
*Provenance: iqafsim.py — IMGMETRICS operator registry. This per-op note is generated by tools/opdocs.py md (do not hand-edit).*
© 2026 Kazufumi Furuse — Fullseye operator documentation. Licensed under Apache-2.0.