sp_lowlands_center — 2D `subpix` op

• Data kinds: image → contour

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

• HALCON equivalent: lowlands_center (the HALCON reference is a useful guide to its meaning and parameters)

sp_lowlands_center: 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

Returns the centroid of minimum 'basins' (flat regions lower than their surroundings) (equivalent to HALCON `lowlands_center`).

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

`sp_plateaus と同じ量子化による平坦領域抽出を行った上で、外周の画素がすべて厳密に高い（領域極小である）ものだけを残し、さらに深さ（外周の最小値との差）が min_depth = 0.01 + 0.40*a 以上のものだけを採用する。b` は未使用。戻り値は CONTOUR、各盆地につき 1 点（重心座標、単位はピクセル）。入力が 200,000 画素を超える場合は安全側で空集合を返す。

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_lowlands_center 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_max_sub_pix · sp_local_min_sub_pix · sp_saddle_points_sub_pix · sp_critical_points_sub_pix · sp_plateaus

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

sp_lowlands_center — 2D subpix op