daijroandClaude Opus 5.5 ddfa566d7d Render: 8 and 16 bpc quantisation rounds with floor in the browser ...

Cause: quantize_px rounded with `(v + 0.5) as u32 as f32`. Converting back
from u32 is several instructions in V8's wasm code on x86 (no unsigned
conversion), so quantising a 1080p layer took about 15 ms in the browser:
every 8/16 bpc layer is quantised after its source and every effect, and
the CPU compositor quantises the comp after every layer.

Fix: round_half_up uses floor in wasm (one instruction there) and keeps the
integer conversion elsewhere (x86-64's baseline has no floor instruction,
where floor is slower). The values are the same: both round non-negative
values half up. About 1.5x faster quantising in the browser (15 -> 10 ms
per 1080p layer in a wasm micro-benchmark), unchanged on the desktop.

Tests: color::tests::rounding_forms_agree: both forms agree on 0..=levels
in sixteenths (exact halves included) and on 100 001 products, at 8 and
16 bpc.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

2026-10-09 16:44:49 -05:00

..

src

Render: 8 and 16 bpc quantisation rounds with floor in the browser

2026-10-09 16:44:49 -05:00

Cargo.toml

Merge main into IO-2/SHP-5/OUT-2/PRV-2 work

2026-10-02 22:39:47 -04:00