gray op• Data kinds: image → image
• Call: fullseye.apply(img, "invert", a=0.5, b=0.5) (the 2-D model is one image plus two scalar knobs a,b∈[0,1])
• HALCON equivalent: invert_image (the HALCON reference is a useful guide to its meaning and parameters)
*The figure is the actual output on a synthetic 128×128 input. Left: input, right: output. Point clouds are drawn as a top-down scatter (brightness = z), 1-D series as a line plot, volumes as the maximum-intensity projection along z, videos as the middle frame, complex images as magnitude; return values that are not pictures are shown as the values themselves.*
*Knob a does not change the output (measured: identical at 0.1 / 0.5 / 0.9).*
*Knob b does not change the output (measured: identical at 0.1 / 0.5 / 0.9).*
On other images (synthetic scene / photo / coins. Top row: inputs, bottom row: their outputs. Knobs at default):
▸ invert: other inputs (docs site)
*The 4th column is a colour (H,W,3) input. This op handles colour without crossing channels (it does not convolve the colour channel as a third spatial axis).*
Tone inversion (negative-positive reversal). Equivalent to HALCON's `invert_image` (Invert an image.).
> The detailed description below is the original text — the summary and the headings are translated.
`1 - clip(v,0,1) を返すだけ。a, b` は未使用。
• 入力を先に [0,1] へ clip してから反転するので、範囲外の値は飽和してから反転される(1.3 → 0、-0.2 → 1)。値域が [0,1] でない配列は前段で正規化しておくこと。
• 返り値は入力と同形の float、値域 [0,1]。NaN は clip を素通りして NaN のまま返る(`ops.py 直登録の op なので backend の guard は掛からない —— 非有限を止めたいなら fullseye.apply 経由で on_error="raise"`)。
• 2 回掛けると元に戻る(対合)。region に掛ければ前景/背景が入れ替わるが、region 用には `invert_region`(補集合)がある。
• 使いどころ: 暗い対象を `threshold で「明るい側」として拾う前の反転、dc_rpca_sparse の暗い残差や xpil_contour` の黒い線を正の信号にする、距離変換の「内側ほど暗い」を「内側ほど明るい」に読み替える。
• 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.
invert 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
gray)gamma · quantize_uniform · quantize_lloyd_max · quantization_error · dither_ordered · dither_floyd_steinberg · companding_mu_law · banding_map
*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.