geometry op• Data kinds: image → image
• Call: fullseye.apply(img, "rescale_img", a=0.5, b=0.5) (the 2-D model is one image plus two scalar knobs a,b∈[0,1])
• HALCON equivalent: zoom_image_factor (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):
▸ rescale_img: knob a sweep (docs site)
Sweeping knob b (0.1 / 0.5 / 0.9, the other knob at its default):
▸ rescale_img: knob b sweep (docs site)
On other images (synthetic scene / photo / coins. Top row: inputs, bottom row: their outputs. Knobs at default):
▸ rescale_img: other inputs (docs site)
*The 4th column is a colour (H,W,3) input. This op handles colour without crossing channels (it does not convolve the colour channel as a third spatial axis).*
Isotropic centre-preserving rescale by s = 0.7 + 0.6·a, canvas kept.
b = interpolation order — (0, 1, 3, 3)[min(3, int(4b))] (0 = nearest neighbour, 1 = bilinear, 3 = cubic spline). b=0.5 is order 3 and, against the default from the time when b was dead (ndimage order=3), is bit-identical.
★2026-09-02: until then rescale_img / zoom_image_factor / zoom_image_size were all 3 the same implementation (measured: maximum mutual differences 0.0 and 4.9e-14), and none of the 3 used b. The 3 roles were separated:
• rescale_img — 1 isotropic factor + interpolation order (this function)
• zoom_image_factor— 2 factors, vertical and horizontal (HALCON's ScaleHeight/ScaleWidth)
• zoom_image_size — target size specified (the output shape changes)
The HALCON name was also reassigned from zoom_image_size → zoom_image_factor to match reality (because this op is driven by a factor, not a size).
• gallery2d_geometry 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.
rescale_img 0.50 0.50
▸ Load this pipeline · Load & run
• gallery2d_geometry — py -3.11 examples/gallery2d_geometry.py
image as input)identity · gaussian · mean_box · bilateral · unsharp · median · min_filter · max_filter
geometry)rotate_img · deskew · affine_warp · sk_swirl · mirror_image · transpose_region · rotate_image · zoom_image_factor
*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.