Lilith River 3b11e2f577 feat: support palette (ColorMap) image decoding
Read the ColorMap tag (320) for RGBPalette images and return raw
palette indices as the decoded data with ColorType::Palette(n).

Changes:
- Read and validate ColorMap tag during IFD parsing (3 * 2^bps entries)
- Return ColorType::Palette from colortype() for RGBPalette images
- Accept Palette in expand_chunk validation (standard + sub-byte depths)
- Expose color_map() method on Decoder for palette lookup
- Add tests for 1-bit, 4-bit, 8-bit palette images with checksums
- Add test verifying ColorMap accessibility and structure

The decoder returns raw palette indices; consumers apply the lookup
using the color map returned by Decoder::color_map().
2026-03-09 21:03:30 -06:00
2026-02-14 18:04:07 +01:00
2026-03-06 09:31:23 +01:00
2018-03-12 18:26:44 +01:00
2026-03-08 03:00:15 +01:00
2018-03-12 13:43:42 +01:00

image-tiff

Build Status Documentation Further crate info

TIFF decoding and encoding library in pure Rust

Supported

Features

  • Baseline spec (other than formats and tags listed below as not supported)
  • Multipage
  • BigTIFF
  • Incremental decoding

Formats

This table lists photometric interpretations and sample formats which are supported for encoding and decoding. The entries are ColorType variants for which sample bit depths are supported. Only samples where all bit depths are equal are currently supported. For example, RGB(8) means that the bit depth [8, 8, 8] is supported and will be interpreted as an 8 bit per channel RGB color type.

PhotometricInterpretation UINT Format IEEEFP Format
WhiteIsZero Gray(8|16|32|64) Gray(32|64)
BlackIsZero Gray(8|16|32|64) Gray(32|64)
RGB RGB(8|16|32|64), RGBA(8|16|32|64) RGB(32|64), RGBA(32|64)
RGBPalette
Mask
CMYK CMYK(8|16|32|64) CMYK(32|64)
CMYKA CMYKA(8)
YCbCr
CIELab

Compressions

Decoding Encoding
None ✓ ✓
LZW ✓ ✓
Deflate ✓ ✓
PackBits ✓ ✓
Fax4 ✓ not yet
JPEG ✓ not yet
ZSTD ✓ not yet

Not yet supported

Formats and interpretations not listed above or with empty entries are unsupported.

  • Baseline tags
    • ExtraSamples
  • Extension tags

Fuzzing

This crate uses cargo-fuzz in order to test the image parser.

After installing it with cargo install cargo-fuzz on a nightly rustc, the fuzzing harness can be run with recommended settings using cargo fuzz run decode_image -snone -- -timeout=5.

S
Description
Fork of https://github.com/image-rs/image-tiff, modifying the tiff crate to be able to read RGBPalette tiffs.
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