arithmetic op• Data kinds: image → image
• Call: fullseye.apply(img, "atan_image", a=0.5, b=0.5) (the 2-D model is one image plus two scalar knobs a,b∈[0,1])
• HALCON equivalent: atan_image (the HALCON reference is a useful guide to its meaning and parameters)
An arctangent LUT mapping [0,1] to [0,1] via `arctan(x) / (pi/2). The slope is greatest near the center (x is about 0.5) and becomes gentler toward both ends - an S-curve that, unlike asin_image, enhances contrast in the middle rather than at the ends. Stands in for HALCON's atan_image` (Calculate the arctangent of an image.).
> The detailed description below is the original text — the summary and the headings are translated.
`a, b` は未使用。傾きの急峻さを変える調整点は無い固定カーブ。
• 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
arithmetic)abs_image · sqrt_image · exp_image · log_image · sin_image · cos_image · asin_image · acos_image
*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.