libheif includes the heif-convert command that PhotoPrism can use to convert HEIC images to JPEG. For the source code and additional documentation, see https://github.com/strukturag/libheif.
These tar.gz archives with pre-built binaries may be used together with the installation packages available at dl.photoprism.app/pkg/linux/ to install PhotoPrism on compatible Linux distributions without building it from source:
Running this as root will install the latest available version of libheif in /usr/local:
xxxxxxxxxxbash <(curl -s https://raw.githubusercontent.com/photoprism/photoprism/develop/scripts/dist/install-libheif.sh)
Please check the files listed at https://dl.photoprism.app/dist/libheif/ to see if binaries are available for your Ubuntu or Debian base distribution and CPU architecture.
Advanced users can otherwise use the following script to build custom binaries from source (changes may be needed):
https://raw.githubusercontent.com/photoprism/photoprism/develop/scripts/dist/build-libheif.sh
libheif is distributed under the terms of the GNU Lesser General Public License and the included sample applications are distributed under the terms of the MIT License:
https://github.com/strukturag/libheif/blob/master/COPYING