gray op• Data kinds: image → image
• Call: fullseye.apply(img, "sk_adjust_log", a=0.5, b=0.5) (the 2-D model is one image plus two scalar knobs a,b∈[0,1])
• HALCON equivalent: log_image (the HALCON reference is a useful guide to its meaning and parameters)
Logarithmic tone transform (log transform). A tonal correction that lifts dark areas using a logarithmic curve of the form `out = gain * log(1 + in)` -- similar in use to gamma correction, but with a nonlinear curve that lifts only the darkest areas more strongly.
> The detailed description below is the original text — the summary and the headings are translated.
HALCON の log_image(Calculate the logarithm of an image.)に相当。実装は `exposure.adjust_log(clip(v,0,1), gain=0.5+1.5*a) の結果を [0,1] へ clip したもの —— a は gain を 0.5〜2.0 に振る。b は未使用。gain が 1 を超えると出力が 1 を僅かに超えることが実測されている(a=0.5 で max=1.1380)ため、image 契約([0,1])を守るために出口で明示的に clip している —— パイプライン内では ops._apply` の段間 clip と同じ値になるためビット不変だが、直接呼び出した時の白飛びの見え方は clip 追加前と変わる。
• gallery2d_gray_arith 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.
• gallery2d_gray_arith — py -3.11 examples/gallery2d_gray_arith.py
image as input)identity · gaussian · mean_box · bilateral · unsharp · median · min_filter · max_filter
gray)gamma · invert · scale_clip · equalize · sigmoid · clahe · sk_adapthist · sk_enhance_contrast
*Provenance: ops.py — 2D 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.