normal_map_decode — GFX2D `light` op

• Data kinds: rgb → normalmap

• Call: import gfx2d; gfx2d.normal_map_decode(rgb) (or opsgfx2d.get("normal_map_decode"))

Usage

Tangent-space normal map `rgb in [0, 1] to unit vectors (H, W, 3)`.

The usual encoding `n = 2c - 1` followed by normalisation. The result is

the `normalmap` sort the rest of the library already speaks, so a decoded

map can go straight into the 3-D normals family.

Raises ValueError: a pixel whose decoded vector has zero length (the encoded

colour was exactly mid-grey), because normalising it would silently invent a

direction.

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)

• gfx2d_scene — py -3.11 examples/gfx2d_scene.py

Ops the type connects to (they accept `normalmap` as input)

normal_map_shade

Same category (`light`)

radial_light · light_mask · normal_map_shade · shadow_cast_2d

*Provenance: gfx2d.py — GFX2D operator registry. This per-op note is generated by tools/opdocs.py md (do not hand-edit).*

normal_map_decode — GFX2D light op