sp_local_max_sub_pix — 2D `subpix` op

• Data kinds: image → contour

• Call: fullseye.apply(img, "sp_local_max_sub_pix", a=0.5, b=0.5) (the 2-D model is one image plus two scalar knobs a,b∈[0,1])

sp_local_max_sub_pix: 入力 → 出力

*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).*

Usage

Detects local maxima of the gray-value surface with sub-pixel accuracy (an alternative implementation of HALCON `local_max_sub_pix. halcon=""`: not double-claimed under that name because an existing core op already covers the same coordinates).

> The detailed description below is the original text — the summary and the headings are translated.

3x3 近傍に 2 次曲面 `z = a0+a1 x+a2 y+a3 x^2+a4 y^2+a5 xy を最小二乗フィットし、勾配 0 の点へのオフセットを解いてサブピクセル位置を求める（ヘッセ行列が退化する場合は 1 次元放物線補間にフォールバック）。aは極大の顕著さ（周囲の最小値からの深さ）のしきい値を 0.01〜0.31 に振る（thr = 0.01 + 0.30*a）。b は未使用。戻り値は CONTOUR、座標の単位は入力画像のピクセル（小数値＝サブピクセル）。検出点数はcount_contours` で数えられる。

Detailed usage guide

• gallery2d_geometry family guide

Background guides (the physics and conventions behind this op)

• measurement_uncertainty — 計測の不確かさと校正の知識 — 「測れている」を主張するために

References (sample data, literature)

• 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.

Try it in Studio

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.

sp_local_max_sub_pix 0.50 0.50

▸ Load this pipeline · Load & run

Runnable examples (verified samples that actually call this op)

• gallery2d_geometry — py -3.11 examples/gallery2d_geometry.py

Ops the type connects to (they accept `contour` as input)

identity · select_contours · smooth_contours · fit_line_contours · contours_to_region · count_contours · total_length · select_contours_xld

Same category (`subpix`)

sp_local_min_sub_pix · sp_saddle_points_sub_pix · sp_critical_points_sub_pix · sp_plateaus · sp_lowlands_center

*Provenance: ops.py — 2D operator registry. This per-op note is generated by tools/opdocs.py md (do not hand-edit).*

sp_local_max_sub_pix — 2D subpix op