halcon_ext op• Data kinds: contour → feature
• Call: fullseye.apply(img, "hx_distance_sc", a=0.5, b=0.5) (the 2-D model is one image plus two scalar knobs a,b∈[0,1])
• HALCON equivalent: distance_sc (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):
▸ hx_distance_sc: knob a sweep (docs site)
*Knob b does not change the output (measured: identical at 0.1 / 0.5 / 0.9).*
Stages (the ops that come before → this op, left to right):
▸ hx_distance_sc: stages (docs site)
The minimum distance from a horizontal segment (row a*H) to the contour (a feature).
Returns the minimum vertical distance |row - a*H| from the horizontal line at row a*H to the vertices of all contours, divided by max(H, 1) and capped at 1, as np.float64. Columns are ignored, so the line is treated as a horizontal line spanning the full image width.
• a → row position of the horizontal line (0 is the top row, 1 is 1 below the bottom row).
• b is unused.
• 0.0 if the contours have no points (indistinguishable from a point lying on the line).
The distance is to the vertices, so even a contour that crosses the line between 2 adjacent vertices does not give 0 but "the row difference of the nearer vertex". The distance from a point to a contour is hx_distance_pc; from a point to a region hx_distance_pr.
• gallery2d_halcon_ext 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.
threshold 0.50 0.50 sk_find_contours 0.50 0.50 hx_distance_sc 0.50 0.50
▸ Load this pipeline · Load & run
• gallery2d_halcon_ext — py -3.11 examples/gallery2d_halcon_ext.py
feature as input)halcon_ext)hx_gen_circle · hx_gen_ellipse · hx_gen_rectangle2 · hx_gen_checker_region · hx_gen_grid_region · hx_gabor · hx_fit_surface1 · hx_fit_surface2
*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.