ncc_locate — 2D `matching` op

• Data kinds: image → match

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

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

ncc_locate: input → output

*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).*

Usage

Finds the best position using template matching based on normalized cross-correlation (NCC). Equivalent to HALCON's find_ncc_model (Find the best matches of an NCC model in an image.).

a, b are unused — the template is not an argument but is pre-registered in the thread-local _MATCH_CTX with set_match_template (the convention shared by the matching ops; see the docstring of _MatchCtx). It computes _ncc_map (the NCC correlation map, [-1,1] by the definition of Lewis 1995) and returns the position of its maximum as [correlation, y, x]. If no template is set, or the input is not a 2-D image, it returns [0,0,0] (no-match) — fail-closed. Rotation and scale changes are not supported (_shape_locate handles rotation).

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.

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.

ncc_locate 0.50 0.50

▸ Load this pipeline · Load & run

Runnable examples (verified samples that actually call this op)

• gallery2d_contour_measure — py -3.11 examples/gallery2d_contour_measure.py

• poc_search_sweep_width — py -3.11 examples/poc_search_sweep_width.py

• poc_template_tracking — py -3.11 examples/poc_template_tracking.py

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

identity

Same category (`matching`)

shape_locate

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

ncc_locate — 2D matching op