threshold_sub_pix — 2D `contour` op

• Data kinds: image → contour

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

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

Usage

Level-crossing (contour-line) extraction using the marching squares method (`skimage.measure.find_contours). Returns, as a contour with sub-pixel accuracy, the positions crossing a specified gray level (0.2+0.5*a). Corresponds to HALCON's threshold_sub_pix` (Extract level crossings from an image with subpixel accuracy.).

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

`a がクロッシングを取るレベルを振る。b` は未使用。skimage が無い

環境ではこの分岐は呼べない。

Detailed usage guide

• gallery2d_contour_measure family guide

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.

Runnable examples (verified samples that actually call this op)

• gallery2d_contour_measure — py -3.11 examples/gallery2d_contour_measure.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 (`contour`)

select_contours · smooth_contours · fit_line_contours · contours_to_region · sk_find_contours · edges_sub_pix · lines_gauss · select_contours_xld

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

threshold_sub_pix — 2D contour op