bridge op• Data kinds: image → qimage
• Call: fullseye.apply(img, "img_to_monogenic", 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.*
Sweeping knob a (0.1 / 0.5 / 0.9, the other knob at its default):
▸ img_to_monogenic: knob a sweep (docs site)
Sweeping knob b (0.1 / 0.5 / 0.9, the other knob at its default):
▸ img_to_monogenic: knob b sweep (docs site)
On other images (synthetic scene / photo / coins. Top row: inputs, bottom row: their outputs. Knobs at default):
▸ img_to_monogenic: 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).*
Build the single-scale monogenic signal of the image (a quaternion field (H,W,4), sort qimage).
The ledger's monogenic_signal (Felsberg & Sommer 2001) itself: applies a log-radial raised-cosine band-pass, pairs it with its Riesz pair and packs them into the quaternion (band-pass image, R1, R2, 0). tb_monogenic_amplitude / tb_monogenic_phase / tb_monogenic_orientation accept only a qimage of this form (passing a colour quaternion tb_rgb_to_quaternion is rejected as "not a monogenic signal"), so this is the entry to that family.
• a → centre wavelength wavelength_px = 3 + 12 * a pixels (3 to 15 px, 9 px at a=0.5; the smaller, the finer the structures it responds to). ★Until 2026-10-07 it was 8 * (0.25 + 1.75 * a), and a=0 mapped to 2 px (Nyquist), which monogenic_signal always rejected —— the lower end was raised to 3 px, and the 9 px at a=0.5 was left unchanged.
• b → bandwidth bandwidth_octaves = 1.0 * (0.25 + 1.75 * b) octaves (1.125 at b=0.5).
• Returns: (H, W, 4) float64. The range depends on the input and does not fit in [0,1] (the Riesz pair is signed).
• gallery2d_bridge 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.
img_to_monogenic 0.50 0.50
▸ Load this pipeline · Load & run
• gallery2d_bridge — py -3.11 examples/gallery2d_bridge.py
qimage as input)identity · tb_quaternion_to_rgb · tb_quat_norm · tb_quat_conjugate_image · tb_quat_normalize_image · tb_monogenic_amplitude · tb_monogenic_phase · tb_monogenic_orientation
bridge)img_to_points · img_to_keypoints · img_to_signal · img_to_projection_profile · img_to_counts · img_to_matrix · img_to_video · img_to_volume
*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.