cv_min_eigen — 2D edges op

Data kinds: imageimage

Call: fullseye.apply(img, "cv_min_eigen", a=0.5, b=0.5) (the 2-D model is one image plus two scalar knobs a,b∈[0,1])

HALCON equivalent: points_harris (the HALCON reference is a useful guide to its meaning and parameters)

cv_min_eigen: 入力 → 出力

*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).*

Usage

Corner strength via the minimum eigenvalue (Shi-Tomasi family, OpenCV implementation). Returns the smaller of the two eigenvalues of the gradient structure tensor - unlike Harris, there is no weighting (dependent on k), making it a more direct measure of "good feature point"-ness (the same kind of criterion used internally by cv_good_features).

> The detailed description below is the original text — the summary and the headings are translated.

HALCON の points_harris に相当(近似。アルゴリズムは別物)。実装は `cv2.cornerMinEigenVal(v, blockSize=3+2*int(a*2))` を正規化したもの —— a は評価に使う近傍サイズ(blockSize)を 3, 5, 7 に振る。b は未使用。

Detailed usage guide

gallery2d_edges family guide

References (sample data, literature)

• 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.

Try it in Studio

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.

cv_min_eigen 0.40 0.50

▸ Load this pipeline  ·  Load & run

Runnable examples (verified samples that actually call this op)

gallery2d_edgespy -3.11 examples/gallery2d_edges.py

Ops the type connects to (they accept image as input)

identity · gaussian · mean_box · bilateral · unsharp · median · min_filter · max_filter

Same category (edges)

sobel_mag · prewitt_mag · roberts_mag · dog · grad_dir · log · corner_response · sk_scharr


*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.