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rw2: support raw format 8 (V8), fix panic on undersized raw sections - #60
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akilegaspi wants to merge 2 commits into
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decode_panasonic computes bit-pump block offsets assuming the classic
9/8-bytes-per-pixel Panasonic packing. Newer bodies (S5 II / S5 II X /
S1R II / G9 II generation) write a ~1 byte/pixel compression, so the
raw section is ~25% smaller than the assumed packing and the unguarded
slice at the top of each row group panics on the rayon decode threads:
range start index 26673152 out of range for slice of length 25587216
Add a minimum-size guard at both decode_panasonic call sites, computed
from the block-aligned offset of the last row group, so these files
return a descriptive Err instead. The bound is strictly below the size
of any working 9/8-packed file, so existing decodes are unaffected.
Verified with a DC-S5M2X file (6000x4008): previously panicked, now
returns Err("RW2: raw section is 25587216 bytes, too small for
6008x4008; unsupported compression variant").
Fixes pedrocr#59
Port of rawspeed's PanasonicV8Decompressor (LGPL-2.1). V8 files carry a RawFormat tag (0x002d) that is now checked before decoding to select the decoder generation: - RawFormat 8: Huffman-coded strips of 2x2 CFA tiles (lossless-JPEG-like prediction). All V8 tags are validated up front: identity gamma curve, zero shift-down, clip value 0xffff, consistent strip tables, grid tiling covering the whole image, and in-bounds strip data. Anything unexpected returns a descriptive Err instead of decoding garbage. - RawFormat 4..=7 or tag absent: legacy decoders, with the undersized-buffer guard from the previous commit kept as a safety net. - Any other version: clean Err. The strip bitstream is MSB-first with the bits of each byte reversed; each strip starts from the 2x2 initial prediction in the metadata and each symbol is a difference category plus JPEG-style extended diff bits. Also adds camera entries for DC-S5M2 / DC-S5M2X (blackpoint 512, whitepoint 16383, RGGB, rawspeed color matrix). Verified against DC-S5M2X files (6008x4008, RawFormat 8): decode succeeds with sane levels (min ~= blackpoint, max = whitepoint) and a normalized correlation of 0.87 with macOS ImageIO's native decode of the same file (raw Bayer vs. demosaicked render, so <1.0 is expected).
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Fixes #59.
Summary
Adds support for Panasonic RW2 raw format 8 (V8) — the Huffman-coded strip encoding written by the S5 II / S5 II X / S1R II / G9 II generation — and fixes the out-of-bounds panic these files triggered in the legacy
decode_panasonicpath:Changes
1. Generation validation before decoding. The
RawFormattag (0x002d) is read before any pixel decoding and selects the decoder:8→ the new V8 decoder4..=7or tag absent → the legacy decoders, unchangedErr("RW2: unsupported raw format version …")2. V8 decoder (port of rawspeed's
PanasonicV8Decompressor, LGPL-2.1 — V8 is lossless-JPEG-style prediction over strips of 2×2 CFA tiles):RevMsbPump)Errinstead of decoding garbage or panicking3. Safety net for legacy paths.
panasonic_min_buf_size()guards bothdecode_panasoniccall sites: the bound is the block-aligned bit-pump offset of the last row group, strictly below the size of any working 9/8-packed file, so no file that decodes today can be rejected.4. Camera entries for DC-S5M2 / DC-S5M2X (blackpoint 512, whitepoint 16383, RGGB, rawspeed color matrix).
Verification
cargo testpasses (5 passed, 2 ignored).