Imagequant library converts RGBA images to palette-based 8-bit indexed images, including alpha component. It's ideal for generating tiny PNG images and nice-looking GIFs.
Image encoding/decoding isn't handled by the library itself, bring your own encoder. If you're looking for a command-line tool, see pngquant.
This library can be used in C programs via imagequant-sys Rust package.
bash
git clone https://github.com/ImageOptim/libimagequant
cd imagequant-sys
cargo build --release
See library documentation for more details.
Add to Cargo.toml:
toml
[dependencies]
imagequant = "4.0.0-beta.4"
See docs.rs for the library API documentation.
Libimagequant is dual-licensed:
libimagequant v2 used to be a C library. libimagequant v4 is written entirely in Rust, but still exports a C interface for C programs. You will need to install Rust 1.56+ to build it, and adjust your build commands. If you do not want to upgrade, you can keep using the C version of the library in the 2.x branch of the repo.
Files for C/C++ are now in the imagequant-sys/ subdirectory, not in the root of the repo. There is no configure && make any more.
To build the library, install Rust, and run:
bash
cargo build --release
It produces target/release/libimagequant.a static library. The API, ABI, and header files remain the same, so everything else should work the same.
If you're building for macOS or iOS, see included xcodeproj file (add it as a subproject to yours).
If you're building for Android, run rustup target add aarch64-linux-android; cargo build --release --target aarch64-linux-android and use target/aarch64-linux-android/release/libimagequant.a. Same for cross-compiling to other platforms. See rustup target list.
The API and ABI of this library remains the same. It has the same sover, so it can be a drop-in replacement for the previous C version.
This library is now a typical Rust/Cargo library. If you want to set up off-line builds or override dependencies, it works the same as for every other Rust project. See Cargo docs for things like cargo fetch or cargo vendor (but I don't recommend vendoring).
makeconfigure is gone (there are no C compilers or deps to configure any more!), but make install still exists. You can configure prefix, etc. as make variables:
bash
make shared
make DESTDIR=. PREFIX=/usr/local install
Rust 1.56 is a build-time dependency (the Makefile uses cargo build). No runtime deps (apart from Cargo-internal ones). OpenMP has been dropped entirely.
cargo-cIn case the Makefile doesn't build a proper library, please send pull requests. But another option is to use cargo-c tool that is smarter about linking so/dylib properly, and generates an accurate pkg-config file.
bash
cargo install cargo-c
cargo cinstall --prefix=/usr/local --destdir=.
This makes Rust 1.56 and cargo-c package a build-time dependency. No runtime deps (apart from Cargo-internal ones). OpenMP has been dropped entirely.
pngquant v2 can use this library as a dynamic library. However, pngquant v4 does not support unbundling. It uses this library as a Cargo dependency via its Rust-native interface. The shared libimagequant library exports only a stable ABI for C programs, and this interface is not useful for Rust programs.
If you've used the imagequant-sys crate, switch to the higher-level imagequant crate. The imagequant v4 is almost entirely backwards-compatible, with only tiny changes that the Rust compiler will point out (e.g. changed use of c_int to u32). See docs.