For openSUSE Tumbleweed run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:sbrabec:heif/openSUSE_Tumbleweed/home:sbrabec:heif.repo
zypper refresh
zypper install gimp
For openSUSE Factory snapshot run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:sbrabec:heif/openSUSE_Factory_snapshot/home:sbrabec:heif.repo
zypper refresh
zypper install gimp
For openSUSE Factory run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:sbrabec:heif/openSUSE_Factory/home:sbrabec:heif.repo
zypper refresh
zypper install gimp
For 15.6 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:sbrabec:heif/15.6/home:sbrabec:heif.repo
zypper refresh
zypper install gimp
For 15.4 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:sbrabec:heif/15.4/home:sbrabec:heif.repo
zypper refresh
zypper install gimp