halcon_ext op• Data kinds: image → image
• Call: fullseye.apply(img, "hx_fit_surface2", a=0.5, b=0.5) (the 2-D model is one image plus two scalar knobs a,b∈[0,1])
• HALCON equivalent: fit_surface_second_order (the HALCON reference is a useful guide to its meaning and parameters)

*The figure is the real output on a synthetic 128×128 input. Left: input, right: output (a non-image return value is shown as the value itself).*
Fits the gray values with a second-order polynomial surface by least squares. Corresponds to HALCON's `fit_surface_second_order` (computes gray-value moments and fits a second-order surface).
> The detailed description below is the original text — the summary and the headings are translated.
基底を `[1, x, y, x^2, y^2, xy] に拡張したこと以外は hx_fit_surface1`
と同じ(座標 [-1,1] 正規化 -> 最小二乗 -> [0,1] 正規化)。曲がった照明ムラや
緩い凹凸の背景推定に使う。`a, b` は未使用。
• 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.
hx_fit_surface2 0.50 0.50
▸ Load this pipeline · Load & run
• gallery2d_halcon_ext — py -3.11 examples/gallery2d_halcon_ext.py
image as input)identity · gaussian · mean_box · bilateral · unsharp · median · min_filter · max_filter
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_cooc_feature
*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.