libheif

libheif is an ISO/IEC 23008-12:2017 HEIF and AVIF (AV1 Image File Format) file format decoder and encoder. There is partial support for ISO/IEC 23008-12:2022 (2nd Edition) capabilities.

HEIF and AVIF are new image file formats employing HEVC (H.265) or AV1 image coding, respectively, for the best compression ratios currently possible.

libheif makes use of libde265 for HEIF image decoding and x265 for encoding. For AVIF, libaom, dav1d, svt-av1, or rav1e are used as codecs.

Supported features

libheif has support for:

• HEIC, AVIF, VVC, JPEG-in-HEIF, JPEG2000, uncompressed (ISO/IEC 23001-17:2024)
• alpha channels, depth maps, thumbnails, auxiliary images
• multiple images in a file
• HDR images, correct color transform according to embedded color profiles
• image transformations (crop, mirror, rotate), overlay images
• plugin interface to add alternative codecs
• reading EXIF and XMP metadata
• region annotations and mask images
• decoding of files while downloading (e.g. extract image size before file has been completely downloaded)

Supported codecs:

Format	Decoders	Encoders
HEIC	libde265, ffmpeg	x265, kvazaar
AVIF	AOM, dav1d	AOM, rav1e, svt-av1
VVC	vvdec	vvenc, uvg266
JPEG	libjpeg(-turbo)	libjpeg(-turbo)
JPEG2000	OpenJPEG	OpenJPEG
uncompressed	built-in	built-in

API

The library has a C API for easy integration and wide language support.

The decoder automatically supports both HEIF and AVIF through the same API. No changes are required to existing code to support AVIF. The encoder can be switched between HEIF and AVIF simply by setting heif_compression_HEVC or heif_compression_AV1 to heif_context_get_encoder_for_format().

Loading the primary image in an HEIF file is as easy as this:

heif_context* ctx = heif_context_alloc();
heif_context_read_from_file(ctx, input_filename, nullptr);

// get a handle to the primary image
heif_image_handle* handle;
heif_context_get_primary_image_handle(ctx, &handle);

// decode the image and convert colorspace to RGB, saved as 24bit interleaved
heif_image* img;
heif_decode_image(handle, &img, heif_colorspace_RGB, heif_chroma_interleaved_RGB, nullptr);

int stride;
const uint8_t* data = heif_image_get_plane_readonly(img, heif_channel_interleaved, &stride);

// ... process data as needed ...

// clean up resources
heif_image_release(img);
heif_image_handle_release(handle);
heif_context_free(ctx);

Writing an HEIF file can be done like this:

heif_context* ctx = heif_context_alloc();

// get the default encoder
heif_encoder* encoder;
heif_context_get_encoder_for_format(ctx, heif_compression_HEVC, &encoder);

// set the encoder parameters
heif_encoder_set_lossy_quality(encoder, 50);

// encode the image
heif_image* image; // code to fill in the image omitted in this example
heif_context_encode_image(ctx, image, encoder, nullptr, nullptr);

heif_encoder_release(encoder);

heif_context_write_to_file(ctx, "output.heic");

heif_context_free(ctx);

Get the EXIF data from an HEIF file:

heif_item_id exif_id;

int n = heif_image_handle_get_list_of_metadata_block_IDs(image_handle, "Exif", &exif_id, 1);
if (n==1) {
  size_t exifSize = heif_image_handle_get_metadata_size(image_handle, exif_id);
  uint8_t* exifData = malloc(exifSize);
  struct heif_error error = heif_image_handle_get_metadata(image_handle, exif_id, exifData);
}

See the header file heif.h for the complete C API.

There is also a C++ API which is a header-only wrapper to the C API. Hence, you can use the C++ API and still be binary compatible. Code using the C++ API is much less verbose than using the C API directly.

There is also an experimental Go API, but this is not stable yet.

Compiling

This library uses the CMake build system (the earlier autotools build files have been removed in v1.16.0).

For a minimal configuration, we recommend to use the codecs libde265 and x265 for HEIC and AOM for AVIF. Make sure that you compile and install libde265 first, so that the configuration script will find this. Also install x265 and its development files if you want to use HEIF encoding, but note that x265 is GPL. An alternative to x265 is kvazaar (BSD).

The basic build steps are as follows (--preset argument needs CMake >= 3.21):

mkdir build
cd build
cmake --preset=release ..
make

There are CMake presets to cover the most frequent use cases.

• release: the preferred preset which compiles all codecs as separate plugins. If you do not want to distribute some of these plugins (e.g. HEIC), you can omit packaging these.
• release-noplugins: this is a smaller, self-contained build of libheif without using the plugin system. A single library is built with support for HEIC and AVIF.
• testing: for building and executing the unit tests. Also the internal library symbols are exposed. Do not use for distribution.
• fuzzing: all codecs like in release build, but configured into a self-contained library with enabled fuzzers. The library should not distributed.

You can optionally adapt these standard configurations to your needs. This can be done, for example, by calling ccmake . from within the build directory.

CMake configuration variables

Libheif supports many different codecs. In order to reduce the number of dependencies and the library size, you can choose which of these codecs to include. Each codec can be compiled either as built-in to the library with a hard dependency, or as a separate plugin file that is loaded dynamically.

For each codec, there are two configuration variables:

• WITH_{codec}: enables the codec
• WITH_{codec}_PLUGIN: when enabled, the codec is compiled as a separate plugin.

In order to use dynamic plugins, also make sure that ENABLE_PLUGIN_LOADING is enabled. The placeholder {codec} can have these values: LIBDE265, X265, AOM_DECODER, AOM_ENCODER, SvtEnc, DAV1D, FFMPEG_DECODER, JPEG_DECODER, JPEG_ENCODER, KVAZAAR, OpenJPEG_DECODER, OpenJPEG_ENCODER, OPENJPH_ENCODER, VVDEC, VVENC, UVG266.

Further options are:

• WITH_UNCOMPRESSED_CODEC: enable support for uncompressed images according to ISO/IEC 23001-17:2024. This is experimental and not available as a dynamic plugin. When enabled, it adds a dependency to zlib, and optionally will use brotli.
• WITH_HEADER_COMPRESSION: enables support for compressed metadata. When enabled, it adds a dependency to zlib. Note that header compression is not widely supported yet.
• WITH_LIBSHARPYUV: enables high-quality YCbCr/RGB color space conversion algorithms (requires libsharpyuv, e.g. from the third-party directory).
• ENABLE_MULTITHREADING_SUPPORT: can be used to disable any multithreading support, e.g. for embedded platforms.
• ENABLE_PARALLEL_TILE_DECODING: when enabled, libheif will decode tiled images in parallel to speed up compilation.
• PLUGIN_DIRECTORY: the directory where libheif will search for dynamic plugins when the environment variable LIBHEIF_PLUGIN_PATH is not set.
• WITH_REDUCED_VISIBILITY: only export those symbols into the library that are public API. Has to be turned off for running some tests.

macOS

1. Install dependencies with Homebrew

   brew install cmake make pkg-config x265 libde265 libjpeg libtool
   

2. Configure and build project (--preset argument needs CMake >= 3.21):

   mkdir build
   cd build
   cmake --preset=release ..
   ./configure
   make
   

Windows

You can build and install libheif using the vcpkg dependency manager:

git clone https://github.com/Microsoft/vcpkg.git
cd vcpkg
./bootstrap-vcpkg.bat
./vcpkg integrate install
./vcpkg install libheif

The libheif port in vcpkg is kept up to date by Microsoft team members and community contributors. If the version is out of date, please create an issue or pull request on the vcpkg repository.

Adding libaom encoder/decoder for AVIF

• Run the aom.cmd script in the third-party directory to download libaom and compile it.

When running cmake or configure, make sure that the environment variable PKG_CONFIG_PATH includes the absolute path to third-party/aom/dist/lib/pkgconfig.

Adding rav1e encoder for AVIF

• Install cargo.
• Install cargo-c by executing

cargo install --force cargo-c

• Run the rav1e.cmd script in the third-party directory to download rav1e and compile it.

When running cmake, make sure that the environment variable PKG_CONFIG_PATH includes the absolute path to third-party/rav1e/dist/lib/pkgconfig.

Adding dav1d decoder for AVIF

• Install meson.
• Run the dav1d.cmd script in the third-party directory to download dav1d and compile it.

When running cmake, make sure that the environment variable PKG_CONFIG_PATH includes the absolute path to third-party/dav1d/dist/lib/x86_64-linux-gnu/pkgconfig.

Adding SVT-AV1 encoder for AVIF

You can either use the SVT-AV1 encoder libraries installed in the system or use a self-compiled current version. If you want to compile SVT-AV1 yourself,

• Run the svt.cmd script in the third-party directory to download SVT-AV1 and compile it.

When running cmake or configure, make sure that the environment variable PKG_CONFIG_PATH includes the absolute path to third-party/SVT-AV1/Build/linux/install/lib/pkgconfig. You may have to replace linux in this path with your system's identifier.

You have to enable SVT-AV1 with CMake.

Codec plugins

Starting with v1.14.0, each codec backend can be compiled statically into libheif or as a dynamically loaded plugin (currently Linux only). You can choose this individually for each codec backend in the CMake settings. Compiling a codec backend as dynamic plugin will generate a shared library that is installed in the system together with libheif. The advantage is that only the required plugins have to be installed and libheif has fewer dependencies.

The plugins are loaded from the colon-separated (semicolon-separated on Windows) list of directories stored in the environment variable LIBHEIF_PLUGIN_PATH. If this variable is empty, they are loaded from a directory specified in the CMake configuration. You can also add plugin directories programmatically.

Codec specific notes

• the FFMPEG decoding plugin can make use of h265 hardware decoders. However, it currently (v1.17.0, ffmpeg v4.4.2) does not work correctly with all streams. Thus, libheif still prefers the libde265 decoder if it is available.

Encoder benchmark

A current benchmark of the AVIF encoders (as of 14 Oct 2022) can be found on the Wiki page AVIF encoding benchmark.

Language bindings

• .NET Platform (C#, F#, and other languages): libheif-sharp
• C++: part of libheif
• Go: part of libheif
• JavaScript: by compilation with emscripten (see below)
• NodeJS module: libheif-js
• Python: pyheif, pillow_heif
• Rust: libheif-sys
• Swift: libheif-Xcode

Languages that can directly interface with C libraries (e.g., Swift, C#) should work out of the box.

Compiling to JavaScript / WASM

libheif can also be compiled to JavaScript using emscripten. It can be built like this (in the libheif directory):

mkdir buildjs
cd buildjs
USE_WASM=0 ../build-emscripten.sh ..

Set USE_WASM=1 to build with WASM output. See the build-emscripten.sh script for further options.

Online demo

Check out this online demo. This is libheif running in JavaScript in your browser.

Example programs

Some example programs are provided in the examples directory. The program heif-dec converts all images stored in an HEIF/AVIF file to JPEG or PNG. heif-enc lets you convert JPEG files to HEIF/AVIF. The program heif-info is a simple, minimal decoder that dumps the file structure to the console.

For example convert example.heic to JPEGs and one of the JPEGs back to HEIF:

cd examples/
./heif-dec example.heic example.jpeg
./heif-enc example-1.jpeg -o example.heif

In order to convert example-1.jpeg to AVIF use:

./heif-enc example-1.jpeg -A -o example.avif

There is also a GIMP plugin using libheif here.

HEIF/AVIF thumbnails for the Gnome desktop

The program heif-thumbnailer can be used as an HEIF/AVIF thumbnailer for the Gnome desktop. The matching Gnome configuration files are in the gnome directory. Place the files heif.xml and avif.xml into /usr/share/mime/packages and heif.thumbnailer into /usr/share/thumbnailers. You may have to run update-mime-database /usr/share/mime to update the list of known MIME types.

gdk-pixbuf loader

libheif also includes a gdk-pixbuf loader for HEIF/AVIF images. 'make install' will copy the plugin into the system directories. However, you will still have to run gdk-pixbuf-query-loaders --update-cache to update the gdk-pixbuf loader database.

Software using libheif

• GIMP
• Krita
• ImageMagick
• GraphicsMagick
• darktable
• digiKam 7.0.0
• libvips
• libGD
• Kodi HEIF image decoder plugin
• bimg
• GDAL
• OpenImageIO
• XnView

Packaging status

Sponsors

Since I work as an independent developer, I need your support to be able to allocate time for libheif. You can sponsor the development using the link in the right hand column.

A big thank you goes to these major sponsors for supporting the development of libheif:

• Pinterest
• Shopify
• StrukturAG

License

The libheif is distributed under the terms of the GNU Lesser General Public License. The sample applications are distributed under the terms of the MIT License.

See COPYING for more details.

Copyright (c) 2017-2020 Struktur AG
Copyright (c) 2017-2024 Dirk Farin
Contact: Dirk Farin dirk.farin@gmail.com