halcon_ext op• Data kinds: image → feature
• Call: fullseye.apply(img, "hx_estimate_sl_al_zc", a=0.5, b=0.5) (the 2-D model is one image plus two scalar knobs a,b∈[0,1])
• HALCON equivalent: estimate_sl_al_zc (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).*
Zheng-Chellappa: estimate the slant, corrected by the gradient energy.
Multiplies the same arccos(<I>) slant as hx_estimate_sl_al_lr by a factor (1 + min(e, 1)) based on the mean Sobel gradient magnitude e (capped at 1), divides by pi/2, caps at 1 and returns np.float64. A correction in the direction of "strong gradient = oblique light = large slant".
• a, b are unused.
The correction factor is 1× to 2×, and for images with low mean luminance and strong gradients the result sticks at the upper limit 1. The gradient magnitude also grows with texture and noise, so factors other than illumination make the slant come out too large. Placing gauss_filter in front reduces the noise part of the gradient. Reflectance estimation is hx_estimate_al_am; the azimuth is hx_estimate_tilt_zc.
• 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_estimate_sl_al_zc 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.