arithmetic op• Data kinds: image → image
• Call: fullseye.apply(img, "tan_image", a=0.5, b=0.5) (the 2-D model is one image plus two scalar knobs a,b∈[0,1])
• HALCON equivalent: tan_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).*
A pointwise transform that takes the tangent of pixel values. Corresponds to HALCON's `tan_image` (computes the tangent of an image), but is an approximation with a different normalization convention.
> The detailed description below is the original text — the summary and the headings are translated.
実装は x を [0,1] にクリップし、(x-0.5) を ±0.45π の範囲へ写してから tan を掛け、結果を signed01（符号つき値を [0,1] に写す、0.5 が 0 に対応）で戻す。a, b は未使用。角度域を ±0.45π に抑えているため tan の発散（±90° 付近）には達しない。中間輝度付近で傾きが最大になり、コントラストを強めたい局所帯域を狙うのに使える。
• 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.
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.
tan_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 · 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.