gray op• Data kinds: image → image
• Call: fullseye.apply(img, "it_bit_mask", a=0.5, b=0.5) (the 2-D model is one image plus two scalar knobs a,b∈[0,1])
• HALCON equivalent: bit_mask (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.*
Sweeping knob a (0.1 / 0.5 / 0.9, the other knob at its default):
▸ it_bit_mask: knob a sweep (docs site)
*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):
▸ it_bit_mask: 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).*
bit_mask: logical AND of the 8-bit image with the constant bit mask round(a*255). `b` is ignored.
> The detailed description below is the original text — the summary and the headings are translated.
入力を [0,1] の 2 次元 float64 に揃えたあと `round(x*255)` で 0〜255 の
8 ビット整数に量子化し、定数マスク `m = round(a*255) & 0xFF(a` は
[0,1] に clip)と画素ごとにビット AND を取って、`/255` で [0,1] に戻す。
`a=1 でマスク 255(量子化以外は恒等)、a=0` でマスク 0(全零)、
`a=0.5` で 128(最上位ビットだけ残す=0.5 以上か否かの 2 値化と同じ)。
`b` は未使用。
返り値は入力と同形の float64、値は `k/255 の離散値。a` はビット
パターンとして効くので単調ではない: 0.5(=128)は最上位ビット、0.25 付近
(=64)は上から 2 番目のビットだけを残し、それぞれ独立した縞状の階調平面
(bit plane)が出る。「上位 n ビットを残す」なら `a = (256 - 2**(8-n))/255`
に選ぶ(n=2 で 192/255 ≈ 0.753)。カラー(3 次元)入力はチャネル平均で 2 次元に
落とされる。例外時は fail-soft で入力のクリップ版が返り、台帳に記録される。
ビットシフトは `it_bit_lshift / it_bit_rshift`、階調数の削減は
`it_convert_image_type`。透かし・ステガノグラフィの解析や量子化ノイズの
可視化(下位ビット平面の抽出)に。
• 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.
it_bit_mask 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.