heic_rs::probe rebuilds a grid primary's descriptor, so the pre-scan runs before it; the alpha item that decode reconstructs is counted too; and a thumbnail candidate is scanned before its coded size is resolved, with all candidates sharing one budget.
The primary item and the selected thumbnail are scanned before Context::grid rebuilds their descriptors, every tile reference is counted (repeats included) before the size check dedupes them, and the Exif and XMP items are scanned before they are read.
heic-rs has no aggregate work budget in container parsing: ipma
association entries rescan earlier item ids after each other and an
iloc construction-method-2 extent rebuilds its source item afresh. Cap
the ipma/iloc boxes before heic-rs reads them, and stop probe paying
for a reconstruction heft beyond the file's own size. decode: refuse
files carrying more than 12 container transforms (each would re-copy
the full picture; CodeRabbit row #44), check a grid's payload canvas
against the pixel limit before allocating for it (#48), and to_rgb16
refuses an oversized w*h*ch rather than asking for a multi-gigabyte
buffer.
heic-rs reconstructs iPhone HEVC tiles bit-exactly (checked against libde265), but
its colour stage was 2-27 code values off libheif on every iPhone photo: it ignores
the HEVC VUI and assumes BT.709 limited range. lightcraft-heif now converts YCbCr
itself (nclx, else VUI, else H.265 defaults; nearest chroma, bilinear for odd clap
offsets, as libheif), inherits tile ICC/nclx on grids, follows libheif's imir axis
and clap rounding, and outputs 16-bit RGB. Measured on 30 real and synthetic
files: within 1 code value of libheif (pillow-heif 1.8 / libheif 1.23).
Also: HEIF header reader for import (no pixel decode), embedded thumbnail for small
decodes, nclx/VUI colour hint (shared CICP mapping with PNG), clear 4:2:2/4:4:4
Unsupported error, Format::not_decodable as the one source of "why not" (import
reports "HEIC/HEIF support isn't included in this build"), `.heif` imports.
Release packaging and Nix build with the heif feature, as whats-new promised.
lightcraft_heif::testdata writes lossless (PCM) synthetic HEICs for the tests.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
New crate `lightcraft-heif` (a port of PhotoCraft's photocraft-heif): a thin,
panic-guarded wrapper around heic-rs (pure Rust, pinned =0.1.1) - 8/10-bit,
alpha, grid tiles, container irot/imir/clap, ICC/EXIF/XMP. `lightcraft-codecs`
decodes HEIF behind its non-default `heif` feature (HEVC patents are the
distributor's call, the same policy as PhotoCraft); the apps forward it. HEIC
files stay recognised without the feature: opening one is a clear
"isn't included in this build" error. Fuzz-found heic-rs panics arrive as
regression fixtures (inline bytes, no media committed).
Verified end-to-end on real iPhone HEICs (lightcraft-cli render, rotation and
metadata correct). Note for reviewers: measured here, the engine currently
ignores the decoded image's source-space matrix on export for ANY format (a
true Display-P3 PNG round-trips unchanged); the ICC and space are carried for
all codecs, so this inherits - and does not worsen - existing behaviour.
Co-Authored-By: opencode <noreply@opencode.ai>
Dylan M. Taylor