QLIC

Quick Lossless Image Codec.

QLIC stores still images, RGBA animation, and unsigned 8--24-bit integer samples losslessly. QSW2 carries ICC, CICP, alpha, and photographic metadata. QLIC does not tone-map or infer HDR. The encoder has one automatic policy; it has no effort or quality setting.

This is the only QLIC 1.0 source tree.

Try the web demo. See benchmarks.

Components

Build

Windows requires CMake 3.25 or newer and Visual Studio 2022 or newer.

.\build.ps1
.\scripts\build-rust.ps1
.\scripts\build-web.ps1

WebAssembly also requires LLVM and Node.js.

On Debian or Ubuntu:

sudo apt install build-essential cmake ninja-build pkg-config \
  libpng-dev libwebp-dev libjxl-dev libavif-dev libtiff-dev libwim-dev
cmake -S . -B build -G Ninja -DCMAKE_BUILD_TYPE=Release
cmake --build build
ctest --test-dir build --output-on-failure

To build libraries and tests without importers or LZMS encoding:

cmake -S . -B build -G Ninja -DCMAKE_BUILD_TYPE=Release \
  -DQLIC_BUILD_CLI=OFF -DQLIC_LINUX_LZMS=OFF
cmake --build build
ctest --test-dir build --output-on-failure

Command line

qlic pack input.png output.qlic
qlic unpack input.qlic output.png
qlic info input.qlic --json
qlic verify input.qlic

Use --threads N or --threads all to set CPU use. verify fully decodes and checks a file without writing an image.

Color and metadata

The Windows CLI accepts:

qlic pack input.png output.qlic --color-profile srgb
qlic pack input.png output.qlic --icc display.icc --alpha straight
qlic pack input.tif output.qlic --xmp edit.xmp --exif camera.exif

These options store integer samples without tone mapping. QLIC preserves ordered opaque metadata blocks byte-for-byte. Source adapters import supported ICC, EXIF, XMP, IPTC, and JUMBF records. A neighboring input.xmp Lightroom sidecar is discovered automatically. Explicit metadata options handle records the source adapter cannot expose.

--color-profile rec2100-pq and rec2100-hlg store full-range BT.2020 RGB with the standard PQ (CICP 16) or HLG (CICP 18) transfer identifier. The cross-platform C SDK exposes the same descriptors through qlic_encode_hdr. Both paths preserve the original integer code values; display rendering belongs to the viewer or calling application.

On Windows, PNG output embeds valid EXIF, XMP, JUMBF, and physical-resolution chunks. TIFF output carries ICC, XMP, IPTC, JUMBF, DPI, orientation, and alpha association. Exact sidecars are also written, including duplicate or destination-incompatible records. Premultiplied samples export only to associated-alpha TIFF; PNG export fails instead of changing the samples.

Windows and Linux import PNG, WebP, JPEG XL, TIFF, and BMP when their loaders are present. Linux also imports AVIF. Windows can use installed WIC decoders, including the system JPEG and GIF decoders. Known lossy sources are accepted with a warning that the QLIC file will likely be larger.

C library

find_package(qlic 1.0 CONFIG REQUIRED)
target_link_libraries(app PRIVATE qlic::qlic_static)

Use qlic::qlic for the shared library. The public header is codec/include/qlic/qlic.h. See the SDK guide for ownership, limits, and public entry points.

Rust and WebAssembly

The Rust decoder has no dependencies or C/FFI and forbids unsafe code. The Web package is a static ES module and Wasm binary; it needs no QLIC executable or local service. Both reject unsupported syntax and do not reduce wide or HDR data to RGBA8. See the Rust and WebAssembly guides.

Limits

The decoder supports validated RGBA8 rows and exact rectangular output with progress and cancellation. QST1 regions still require complete entropy reconstruction; the region API bounds destination memory but is not random access. QLIC 1.0 has no incremental input decoder, float/half HDR, RAW development, gain-map interpretation, or Rust encoder. Its HDR contract is exact unsigned 8--24-bit code values with explicit ICC or CICP meaning, including retained PQ and HLG conformance fixtures.

Pin deployed decoders and keep a common interchange format where QLIC is not available.

Evidence

The retained release corpus and every comparison setting are recorded in benchmark-current.md. Results are corpus-specific, and every encoded output is decoded and compared with its source. See architecture.md for design, qualification, and known limits.

Other references: profiles, file format, and support.

Packages

Build the seven local packages with .\scripts\package.ps1. Output goes to dist with checksums and SPDX SBOMs.

Stage a verified unsigned public release bundle with .\scripts\stage-community-release.ps1. It writes the exact upload set under release without committing, tagging, signing, or publishing anything. See community-release.md.

Apache-2.0. The Rust LZMS port also retains its source MIT license.