blend — SHAPE2D morph op

• Data kinds: image2d × image2d → image2d

• Call: import fullseye as fs; fs.ledger.blend(a, b, alpha) (to call the implementation directly, import imagemorph; imagemorph.blend(a, b, alpha); from the registry, opsshape2d.get("blend"))

Usage

Cross-dissolve (1-alpha)·a + alpha·b (a, b have the same shape and lie in [0,1]).

Per-pixel linear interpolation. It does not warp by corresponding points, so with 2 images whose eyes or contours are misaligned you get a double image -- if you want features to overlap into 1, use morph.

• a, b: (H, W) or (H, W, C), same shape. Converted to float64. NaN is silently replaced by 0, +Inf by 1, -Inf by 0 (no exception is raised). The value range is not checked; the result is only clipped to [0, 1], so passing a 0-255 image returns a blown-out picture.

• alpha: blend ratio. Silently clipped to [0, 1] (0 gives a, 1 gives b).

• Returns: float64 of the same shape as the input, [0, 1].

• Failure: ValueError (number of dimensions not 2/3, empty, shape mismatch).

Each frame of morph_sequence mixes the 2 warped images with the same formula as this.

Detailed usage guide

• shape_description_2d 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.

Runnable examples (verified samples that actually call this op)

• image_morph — py -3.11 examples/image_morph.py

• poc_live4d — py -3.11 examples/poc_live4d.py

Ops the type connects to (they accept image2d as input)

warp_tps_image · warp_piecewise_affine · morph · morph_sequence

Same category (morph)

add_frame_corners · warp_tps_image · warp_piecewise_affine · morph · morph_sequence


*Provenance: imagemorph.py — SHAPE2D 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.