halcon_ext op• Data kinds: contour → feature
• Call: fullseye.apply(img, "hx_smallest_rect1_xld", a=0.5, b=0.5) (the 2-D model is one image plus two scalar knobs a,b∈[0,1])
• HALCON equivalent: smallest_rectangle1_xld (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.*
*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).*
Stages (the ops that come before → this op, left to right):
▸ hx_smallest_rect1_xld: stages (docs site)
The area ratio of the axis-aligned bounding box of all contour points (a feature).
Merges all points of a contour dict and returns as np.float64 the product of max - min in the row and column directions (height and width of the axis-parallel bounding rectangle) divided by the image area H*W.
• a, b are unused.
• 0.0 if there are no points. With only 1 point, or all points in the same row/column, the width is 0 and the result is 0.0 (no +1 pixel correction is applied).
Since it is 1 rectangle around all contours together, with 2 separated contours the empty space between them also counts toward the area. For the oriented minimum-area rectangle, use hx_smallest_rect2_xld; for the axis-parallel bounding rectangle of a region, smallest_rectangle1.
• 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_smallest_rect1_xld 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.