bloom — GFX2D post op

• データ種: rgb → rgb

• 呼び出し: import gfx2d; gfx2d.bloom(rgb, threshold=0.8, sigma=4.0, intensity=0.6) (または opsgfx2d.get("bloom"))

使い方

Bleed the bright parts of an image into their neighbourhood.

The classical three steps: isolate what is above `threshold`, blur it by a

Gaussian of `sigma, add intensity` times the result back, clip.

A *linear-light* operator: light spreading in a lens adds radiance. Running

it on sRGB-encoded values makes the halo too strong in the mid-tones —

`srgb_to_linear first, linear_to_srgb` after.

Exact identities: `intensity=0 and threshold >= 1` both return the

input bit for bit, and a black image stays black.

The added energy is *not* conserved by the clip at the end. The suite

measures both halves: on a centred bright blob the Gaussian preserves the

bright mass to 5.0e-16 relative, so everything lost after that is the

clip — on a random scene with a saturated square, 2.69 % of the pixels clip

and 1.65 % of the total energy is thrown away, and neither number is

returned to the caller.

参考(サンプルデータ・文献)

• サンプルデータ カタログ(DL URL / ライセンス) — 2-D は skimage.data(BSD/public)+ 合成、3-D は実データ源(Stanford/PDS 等)の DL URL。

• 演算子の来歴・参考文献 — この op 族の元になった研究/手法の出典。

• アルゴリズムの正典(著者・年)と用途は上記ファミリ使い方ガイドに記載。

実行できる例(この op を実際に呼ぶ検証済みサンプル)

• gfx2d_scene — py -3.11 examples/gfx2d_scene.py

型が繋がる次の op(rgb を入力に取れる)

srgb_to_linear · linear_to_srgb · blend_mode · light_mask · normal_map_decode · vignette · chromatic_aberration · film_grain

同カテゴリ(post)

vignette · chromatic_aberration · film_grain · color_lut · color_grade · dither · palette_quantize

*Provenance: gfx2d.py — GFX2D operator registry. この per-op ノートは tools/opdocs.py md が自動生成(手編集しない)。*

© 2026 Kazufumi Furuse — Fullseye operator documentation. Licensed under Apache-2.0.