halcon_ext op• Data kinds: contour → contour
• Call: fullseye.apply(img, "hx_clip_contours", a=0.5, b=0.5) (the 2-D model is one image plus two scalar knobs a,b∈[0,1])
• HALCON equivalent: clip_contours_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.*
Sweeping knob a (0.1 / 0.5 / 0.9, the other knob at its default):
▸ hx_clip_contours: knob a sweep (docs site)
Sweeping knob b (0.1 / 0.5 / 0.9, the other knob at its default):
▸ hx_clip_contours: knob b sweep (docs site)
Stages (the ops that come before → this op, left to right):
▸ hx_clip_contours: stages (docs site)
On other images (synthetic scene / photo / coins. Top row: inputs, bottom row: their outputs. Knobs at default):
▸ hx_clip_contours: other inputs (docs site)
Clip contours to the image domain (a rectangle keeping the central margins a/b), dropping out-of-range points.
For each contour of a contour dict, keeps only the points inside a rectangle taken within the image, my <= row <= H-1-my, mx <= col <= W-1-mx, discards contours with not even 1 point left, and returns the result.
• a → top/bottom margin my = a*0.4*H (0 to 40% of the height).
• b → left/right margin mx = b*0.4*W (0 to 40% of the width). With a=b=0 it clips to the image range [0, H-1] × [0, W-1].
It only thins out points and does not split contours, so a contour that passes outside the rectangle and comes back takes a shape in which the remaining points are joined directly (a jump). If splitting is needed, use hx_split_contours downstream. A similar op that cuts by a fraction from the centre is hx_crop_contours (width/height specified relative to the centre). It is distinct from xg_clip_contours, which cuts off by line length.
• 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_clip_contours 0.50 0.50
▸ Load this pipeline · Load & run
• gallery2d_halcon_ext — py -3.11 examples/gallery2d_halcon_ext.py
contour as input)identity · select_contours · smooth_contours · fit_line_contours · contours_to_region · count_contours · total_length · select_contours_xld
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.