Elvis33LEandBrandon Thomas fdd7141788 PSD: decode the merged composite only when something consumes it (#846) ...

Every PSD/PSB open decoded the merged image unconditionally, but a normal
layered Photoshop save carries a composite nobody reads: with layers
present and nothing behind the colour channels, the decoded planes went
straight to the drop. That composite is typically about half the file's
bytes, and for ZIP-compressed files the parse-time validation had already
inflated the same stream once - so layered ZIP opens paid the composite
twice for nothing (P18: opening a 20 MP layered PSD measures 1753 ms p50
against a 1000 ms budget).

The composite is now decoded only when a consumer exists: a flattened or
multichannel file (the composite IS the image), or extra alpha/spot
channels behind the colour ones. Layered files without extra channels
skip the decode entirely; everything a layered import shows comes from
the layer records either way.

The parse-time ZIP validation stays: deferring it would break the
corrupt-stream rejection the fuzz tests pin down, and with the decode
skipped, layered ZIP opens now inflate the composite once (validation)
instead of twice.

Co-authored-by: Brandon Thomas <echelon@gmail.com>

2026-10-07 21:10:38 -04:00

..

examples

Large PSBs open with their pixels: decode planes past 2 GiB, plus 4-5 GB PSB fixtures (#375) (#782)

2026-10-07 18:59:39 -04:00

src

PSD: decode the merged composite only when something consumes it (#846)

2026-10-07 21:10:38 -04:00

tests

PSD: decode the merged composite only when something consumes it (#846)

2026-10-07 21:10:38 -04:00

Cargo.toml

Open HEIC/HEIF photos (#355) (#372)

2026-10-07 10:20:40 -04:00