gray op• Data kinds: image → image
• Call: fullseye.apply(img, "xsk3_rank_subtract_mean", a=0.5, b=0.5) (the 2-D model is one image plus two scalar knobs a,b∈[0,1])
Local mean subtraction (skimage `filters.rank.subtract_mean`). Returns the difference obtained by subtracting the mean brightness of the disk neighborhood from each pixel. The skimage implementation scales the difference to 1/2 and shifts it to the middle of the range, to avoid underflow. It cancels global light/dark unevenness and enhances local contrast.
> The detailed description below is the original text — the summary and the headings are translated.
`a は円盤半径(1+int(a*4) で 1〜5)を振る。b` は未使用。8bit 量子化を経由するため元の float64 精度は失われる。
• 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.