libheif

• check for MIAF conformance and add as compatible brand
• signaling of premultiplied alpha
• parse AV1 obu_sequence_header for av1C box
• write pixi box in AVIFs
• save alpha as monochrome in AVIF if possible
• many build fixes (thanks to the numerous external contributors)

• fix writing ispe box in HEIFs
• nclx output profile encoding parameters
• change the way nclx profiles is written so that macOS can read them
• API for listing file brands and checking file type
• fix heif_image_handle_get_depth_image_representation_info()

• new API: may access all (vendor-dependent) auxiliary images (e.g. hdrgainmap, semanticskinmatte, ...)
• change the way images with odd sizes are written so that macOS can read them
• when ICC profile is present, will now write two colr boxes (nclx and ICC) into AVIF files. Also reads files with two colr boxes
• alpha image is now saved as monochrome
• loading of 16bit greyscale PNGs in heif_enc
• heif_enc, option "-E" deprecated
• remove dependency on alloca()
• fix known bugs

• fixed missing inline definition in C++ wrapper

• add dav1d decoder plugin for faster decoding of AVIF images
• support for images having both ICC and NCLX profiles
• save NCLX profiles to AV1/HEVC bitstreams and also read them from the bitstream
• add color profile API to C++ wrapper
• improve rounding in color conversions
• conformant encoding of AVIF images <16 pixels
• many fixes and small improvements

• Integration of rav1e encoder for faster AVIF encoding
• gdk-pixbuf loader now supports AVIF decoding
• color conversion adapts to nclx color profile
• new parameters for heif-enc to set nclx parameters
• support for saving in RGB colorspace (matrix_coefficients=0) for true lossless encoding
• chroma 4:2:2 and 4:4:4 encoding for HEIF
• chroma 4:2:2 and 4:4:4 with AVIF, also with HDR
• monochrome AVIF encoding with AOM plugin
• changed AVIF bitrate control depending on quality parameter
• support for AVIFs with depth images
• AVIF MIME type detection
• update Go API for HDR images
• write libheif and plugin version info to HEIF/AVIF headers
• fix problems with odd image resolutions and very small image sizes
• fix writing too much data into alpha channel images
• lots of bug fixes and handling of corner cases

Support for reading and writing AVIF (8 bit) images through libaom has been added.
Other encoders/decoders can be added with the plugin architecture.
Decoders don't need any code change to also read AVIF images.
Encoders can reuse the existing HEIF code and simply use heif_compression_AV1 to output AVIF.

Other changes:

• HDR image rotation
• HDR to 8 bit conversion
• accept images with only the 'mif1' brand
• bug fixes

• support for HEIX images (10, 12 bit and chroma 4:2:2)
• security limits for maximum image sizes have been increased
• gdk pixbuf loader fixes

• fix crash in gdk-pixbuf plugin
• fix several decoding bugs
• increase security limits for huge files
• modernize cmake build scripts

• thumbnailer: fixed corrupted image output
• thumbnailer: now also works with images having an alpha channel
• generic and proprietary metadata can be added to and read from images (e.g. iptc)
• added man-pages
• other small fixes

• fix regression in reading depth images
• fix access to free'd memory
• internally keep reference to heif_context even when heif_context was free'd, but a heif_image_handle is still in use

Changes:

• added support for encoding monochrome images
• new color-conversion system with support for more color conversion paths (like HDR YCbCr <-> RGB)
• many bugs and security issues have been fixed (CVE-2019-11471)

Changes:

• support for reading and writing color profiles
• support for decoding and encoding 10 bit and 12 bit images
• heif_enc can generate HDR HEIFs from 16 bit PNG
• functions to probe image format
• set arbitrary x265 parameters when encoding HEIFs

• limit number of decoding threads

• Fix reading 'url' boxes
• Fix two compilation problems

Can now generate HEIF files with

• thumbnails
• Exif data
• XMP data

Defines a reader interface to read input data directly from custom sources.

• HEIF thumbnailer for Gnome
• support for XMP metadata
• C++ API
• Go API (experimental)
• compilation fixes for various systems

First implementation of HEIF encoder based on x265.
Supports alpha channels and lossless compression

HEIF still-image decoder with support for

• tiled images
• alpha channels
• thumbnails
• EXIF/XMP data
• depth channels
• multiple images in a HEIF file
• image transformations (crop, mirror, rotate)
• overlay images