perceptual op• Data kinds: image2d × image2d → scalar
• Call: import fullseye as fs; fs.ledger.vifp(ref, dist, data_range: 'float' = 255.0, sigma_nsq: 'float' = 2.0, nscales: 'int' = 4) -> 'float' (to call the implementation directly, import iqafsim; iqafsim.vifp(ref, dist, data_range: 'float' = 255.0, sigma_nsq: 'float' = 2.0, nscales: 'int' = 4) -> 'float'; from the registry, opsimgmetrics.get("vifp"))
> This operator's description has not been translated yet. The original text follows as it is.
VIF の画素領域版(Sheikh & Bovik 2006 §V の scalar GSM、公開 vifp_mscale の規約)。1 = 同一、higher is better。
各スケール s = 1..4: 窓 N = 2^(4−s+1)+1、ガウス σ = N/5(17/3.4、9/1.8、5/1.0、3/0.6)。s > 1 では窓で平滑して 2 間引き。局所統計(μ、σ²、σ12)は
'valid' 相関、g = σ12/(σ1²+1e-10)、σ_v² = σ2² − g σ12、σ1² < 1e-10・σ2² < 1e-10・g < 0 の画素は規約どおり潰す、σ_v² ≤ 1e-10 → 1e-10。
VIF = Σ log10(1 + g² σ1²/(σ_v² + σ_n²)) / Σ log10(1 + σ1²/σ_n²)。非対称(参照の情報量で割る: vif(a, b) ≠ vif(b, a))、コントラスト強調で
1 を超える(TID2013 の作者値も最大 1.1379 = 歪み 17)—— 忠実度でなく情報量の比。入力 (H, W) か (H, W, 3)(3-ch は Y)。
TID2013 の VIFP.txt(論文の「VIFP」、steerable 版の「VIF」とは別行)と 4 桁一致するのは Y′ limited の灰色画像
(`iqatid.tid2013_evaluate(root, vifp, luma="limited_u8")`、3,000 組 max |差| 6.8e-5)。
Raises `ValueError`: 形が違う、最小スケールで窓より小さい、参照が平坦(分母 0)、sigma_nsq ≤ 0。
• 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
scalar as input)luma_limited_u8 · rank_data · tid2013_index
perceptual)fsim · fsimc · fsim_pair · gmsd · gmsd_map · 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.