arithmetic op• Data kinds: image → image
• Call: fullseye.apply(img, "asin_image", a=0.5, b=0.5) (the 2-D model is one image plus two scalar knobs a,b∈[0,1])
• HALCON equivalent: asin_image (the HALCON reference is a useful guide to its meaning and parameters)
*The figure is the real output on a synthetic 128×128 input. Left: input, right: output (a non-image return value is shown as the value itself).*
An arcsine LUT mapping [0,1] to [0,1] via `arcsin(x) / (pi/2). The slope becomes steep near x=0 and near x=1 (the derivative diverges at the ends of the domain), giving the effect of compressing the mid-tones and enhancing contrast at both ends. Stands in for HALCON's asin_image` (Calculate the arcsine of an image.).
> The detailed description below is the original text — the summary and the headings are translated.
`a, b` は未使用。端点付近で数値的に敏感になる点に注意(x が 1 にごく
近いとわずかな量子化誤差でも出力が大きく動く)。
• 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.
The program below has been verified to run (same input as the figure). In Studio's help this block becomes buttons that load and run it on the spot.
asin_image 0.50 0.50
▸ Load this pipeline · Load & run
• 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 · acos_image · atan_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.