classification op• Data kinds: region → feature
• Call: fullseye.apply(img, "classify_shape", a=0.5, b=0.5) (the 2-D model is one image plus two scalar knobs a,b∈[0,1])
*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):
▸ classify_shape: stages (docs site)
A basic shape-classification feature that computes the circularity of the largest connected region. No single corresponding HALCON op is specified.
a, b are unused. For the connected component with the largest area it computes 4π×area / perimeter² and caps it with min(1.0, ...) so that an ideal circle gives 1 (preventing it from slightly exceeding 1 through numerical error). The perimeter is approximated by the number of boundary pixels obtained by subtracting the region's erosion from the region (the same idea as _region_boundary), so it is coarser than a contour-based perimeter. If there is no foreground, it returns 0. As the comment in the code says, it is intended as the basis for processing that "classifies by shape", such as OCR and pass/fail judgement.
• gallery2d_features 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 classify_shape 0.50 0.50
▸ Load this pipeline · Load & run
• gallery2d_features — py -3.11 examples/gallery2d_features.py
feature as input)classification)—
*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.